The 27 member states are expected to agree on an embargo against Iranian oil exports and might even agree to impose some sanctions on the country's central bank.

French Foreign Minister Alain Juppe, speaking at a news conference in Paris last week, said sanctions represent the best hope of avoiding "the military option."

"We have proposed to strengthen these [sanctions] in two fields: an embargo on Iranian oil exports and a freeze on the assets of the Iranian central bank," Juppe said.

"The American Congress has already made decisions in that direction, they were stamped by [U.S.] President [Barack] Obama, [and] we -- the European Union -- are working on them, and I think that on Monday, at the EU foreign ministers meeting, we will be able to come to an agreement on a sanctions package in these two areas."

Two Tracks

The P5+1 group -- which includes Britain, France, Germany, China, Russia, and the United States, and is seeking to negotiate an end to Iran's suspected pursuit of nuclear weapons -- has also stressed its openness to renewed talks.

In a statement, EU foreign policy chief Catherine Ashton, who was speaking on behalf of the P5+1, said the group "has always been clear about the validity of the dual-track approach," referring to the combination of sanctions and diplomacy. However, in the statement Ashton said that Tehran hadn't yet responded to an October 21 letter which laid out the possibility of talks.

German Foreign Minister Guido Westerwelle, in an appearance at the Brookings Institution in Washington, said the bloc is united in its determination to confront Iran.

​​"The European Union will put into place a new and very substantial round of sanctions this coming Monday to forcefully make the point that Iran's behavior on the nuclear issue is unacceptable and a danger to world peace," Westerwelle said.

Speaking in Washington on January 20 after meeting with Westerwelle, U.S. Secretary of State Hillary Clinton said that Iran is heading down a "dangerous path" with its pursuit of a nuclear program.

Clinton also said that Tehran needed to show that it was serious about recent statements indicating a willingness to return to the negotiating table.

"We all are seeking clarity about the meaning behind Iran's public statements that they are willing to engage, but we have to see a seriousness and sincerity of purpose coming from them," Clinton said.

Questions Over Implementation

The main stumbling block is how to freeze the central bank's assets without blocking legitimate trade with the country and how to avoid hurting the population at large.

And with all EU member states already in agreement that an oil embargo is necessary, question marks remain over when the restrictions will be implemented.

The majority of countries, including France, Germany, and the United Kingdom are hoping to set a July 1 date, the same time scale that the United States decided on when it announced similar measures earlier this month.

This would mean that member states would have until the end of June to fulfill existing contracts but that they would have to stop all imports at the start of July as well as refraining from signing any new contracts after that.

Greece has asked for a longer grace period -- of about 9 to 12 months -- to line up alternative supplies. The crisis-hit country is heavily dependent on Iranian oil and is relying on easier credit terms from Tehran to finance its purchases.

Both EU and U.S. diplomats are currently working to secure a deal that would replace imports from Iran with oil from Saudi Arabia. Last year, the EU imported 450,000 barrels a day of Iranian crude, constituting about 20 percent of Iran's total exports.

To ease the concerns of Greece and other large importers such as Spain and Italy, Brussels might also initiate a formal review during the phase-in to ensure that all member states are coping with the disruption.

The attempts to target the central bank are more complicated according to sources who spoke to RFE/RL.

Measures Against Belarus

The European Union also plans to widen the scope of its sanctions against Alyaksandr Lukashenka's regime in Belarus.

So far it has frozen personal assets and imposed visa bans on more than 200 individuals linked to the regime after the violent crackdown on demonstrators that ensued after the flawed presidential election in 2010.

The foreign ministers are expected to decide that human rights offenders in general as well as individuals that prop up the regime economically also can be blacklisted.

The move represents a step away from the rather narrow remit set before, which only targeted people with a direct link to the persecution of demonstrators against alleged voting fraud.

No new names will however be added to the list on January 23, but EU sources claim that there might be up to 140 names being considered under the new framework.

The study has just been published in Geophysical Research Letters.

Lead author Paul Vincent, a geophysicist at Oregon State University, cautions that the findings won't lead to dramatic new ability to detect secret nuclear explosions because of the time lag between the test and the uplift signature, as well as geophysical requirements of the underlying terrain. However, he said, it does "provide another forensic tool for evaluation, especially for the potential explosive yield estimates."

"In the past, satellites have been used to look at surface subsidence as a signal for nuclear testing," said Vincent, an associate professor in OSU's College of Earth, Ocean, and Atmospheric Sciences.

"This is the first time uplift of the ground has correlated to a nuclear test site. The conditions have to be just right and this won't work in every location.

"But it is rather interesting," he added. "It took four years for the source of the uplift signal - a thermal groundwater plume - to reach the surface."

The focus of the study was Lop Nor, a nuclear testing site in China where three tests were conducted - May 21, 1992; May 15, 1995; and Aug. 17, 1995. Vincent and his colleagues analyzed interferometric synthetic aperture radar (InSAR) images from 1996-99 and detected a change in the surface beginning four years after the tests.

Though the uplift was less than two inches, it corresponds to known surface locations above past tests within the Lop Nor test site.

From past studies, the researchers knew that heat from underground detonation of nuclear devices propagates slowly toward the surface. At most sites - including the Nevada National Security Site - that heat signal dissipates laterally when it reaches the water table, which is usually deep beneath the surface.

At Lop Nor, however, the water table is only about three meters below the surface, and the heated groundwater plume took four years to reach that high, lifting the ground above the detonation site slightly - but enough to be detected through InSAR images.

Lop Nor also is characterized by a hard granite subsurface, which helps pipe the heated water vertically and prevents the subsidence frequently found at other testing sites.

A past study by Vincent, published in 2003, first shed light on how subsidence can manifest itself in different ways - from the force of the explosion creating a crater, to more subtle effects of "chimneying," in which the blast opens up a chimney of sorts and draws material downward, creating a dimple at the ground surface.

Before joining the OSU faculty in 2007, Vincent spent several years as a physicist at the Lawrence Livermore National Laboratory.

Vincent said the analysis of nuclear explosions has become a specialized field. Seismology technology can provide an initial estimate of the energy of the explosion, but that data is only good if the seismic waves accurately reflect coupling to the connecting ground in a natural way, he explained. Efforts are sometimes made to "decouple" the explosive device from the ground by creating specializing testing chambers that can give off a false signal, potentially masking the true power of a test.

"Subsidence data combined with seismic data have helped narrow the margin of error in estimating the explosive yield," Vincent noted, "and now there is the potential to use test-related thermal expansion as another forensic tool."

Co-authors on the paper with Vincent include Sean Buckley of the Jet Propulsion Laboratory, Dochul Yang, the University of Texas-Austin, and Steve Carle, of Lawrence Livermore National Laboratory.

The person killed was identified by several media as Mostafa Ahmadi Roshan, a scientist who worked on separating gases at the Natanz uranium enrichment facility, according to the website of a different university from which he graduated around a decade ago.

"This morning a motorbiker attached a bomb to a Peugeot 405, which exploded," the deputy governor of Tehran province, Safar Ali Bratloo, was quoted as saying by the ILNA news agency.

The explosion occurred outside the east Tehran campus of Allameh Tabatai University, at its social sciences faculty.

Ahmadi Roshan was killed and the two wounded passengers were taken to hospital, Bratloo said.

Sharif University, Tehran's elite technical university where the slain scientist had studied, said Ahmadi Roshan was specialised in making polymeric membranes used to separate gas. Iran uses gas separation to enrich uranium.

Three other Iranian scientists were killed in 2010 and 2011 when their cars blew up in similar circumstances. At least two of the scientists had also been working on nuclear activities.

One of the attacks occurred exactly two years ago, on January 11, 2010, killing scientist Masoud Ali Mohammdi.

The current head of Iran's atomic organisation, Fereydoun Abbasi, escaped another such attempt in November 2010, getting out of his car with his wife just before the attached bomb exploded.

Those attacks were viewed by Iranian officials as assassination operations carried out by Israel's Mossad intelligence service, possibly with help from US counterparts.

The latest blast comes amid extremely high international tensions over Iran's nuclear programme, which the West and Israel believe conceals research to develop an atomic bomb.

Israel has threatened to launch air strikes on Iran's nuclear facilities. The United States has said "all options are on the table" in terms of dealing with Iran -- including military action.

Tehran, which has repeatedly denied that its nuclear programme is for anything other than peaceful purposes, has threatened to close the strategic Strait of Hormuz at the entrance to the Gulf if it is attacked. Twenty percent of the world's oil flows through that strait.

Wednesday's car explosion followed confirmation on Monday by the International Atomic Energy Agency that Iran had started uranium enrichment at a fortified underground bunker southwest of Tehran, in Fordo.

The United States, Britain, France, Germany and Italy have viewed that development with alarm, saying it was a violation of UN Security Council resolutions on Iran.

The Fordo site near the holy city of Qom, 150 kilometres (90 miles) southwest of Tehran, has begun enriching uranium to 20-percent purity, the UN atomic watchdog Agency, said late Monday.

US State Department spokeswoman Victoria Nuland said that Iran's enriching of uranium to 20 percent at the site was "a further escalation of their ongoing violations with regard to their nuclear obligations."

"We call on Iran once again to suspend enrichment activities, cooperate fully with the IAEA and immediately comply with all Security Council and IAEA board of governors resolutions," Nuland told reporters in Washington.

Experts point out that the process of obtaining 20-percent enriched uranium represents the lion's share of the work needed to get the material purified to the level of 90 percent or above required for atomic weapons.

Iran, which says its nuclear activities are peaceful, says the material is for its Tehran research reactor to make isotopes for cancer treatments, but Western powers believe it has a much more sinister and destructive purpose.

"This is a provocative act which further undermines Iran's claims that its programme is entirely civilian in nature," British Foreign Secretary William Hague said, echoing the concerns of Washington, Berlin, Paris and elsewhere.

Mark Fitzpatrick from the International Institute for Strategic Studies (IISS) told AFP that the action brings Tehran "closer to being able to quickly produce enough fissile material for a nuclear weapon."

IAEA spokeswoman Gill Tudor said that all nuclear material "remains under the Agency's containment and surveillance" at Fordo.

But the fear is that if Iran decided to expel IAEA inspectors and enrich uranium to weapons-grade purity, Fordo would enable them to produce enough fissile material in a short space of time.

France called the move to enrich uranium at the mountain bunker a "particularly grave violation by Iran of international law."

This, Paris said, leaves "no choice but to strengthen international sanctions and to adopt, with our European partners and all willing countries, measures of an unprecedented scale and severity."

Israel is already preparing for Iran to become a nuclear power and has accepted it may happen within a year, the London Times reported, citing an Israeli security report.

Mark Hibbs from the Carnegie Endowment for International Peace think-tank said: "Israel, which has already warned Iran that it could take military action against installations, is very very worried by this facility ... We are moving into dangerous territory."

Enriching uranium is one of three main areas needed to develop a nuclear arsenal. Iran would also need to make the enriched uranium weapons-ready in a warhead and manufacture a missile to carry it to target.

A report from the IAEA in November, the agency's hardest-hitting to date, included evidence that Western powers said confirmed Iranian efforts in these other two areas.

The United States, the European Union and other allies have sought to tighten the screw since the report -- which Iran dismissed as "baseless" -- by targeting Tehran's crucial oil sector and its central bank.

But analysts said that Iran, which they say is clearly feeling the pinch from the heightened sanctions, could also be planning to use Fordo to strengthen its hand in talks with the West.

"They appear to have taken the decision to acquire a nuclear weapons capability, but not a decision to build the bomb. And that means that they can be dissuaded from doing that," said Albright, now at the Washington-based Institute for Science and International Security (ISIS).

"Because of the opaque nature of leadership in Iran and the lack of deep knowledge on how the leadership is thinking, this escalation could represent an effort by Iran to stake out a tough negotiating position," echoed Hibbs.

Tensions have also been stoked by Iran showing off what it said was a CIA drone it captured using cyberwarfare, while in October Washington alleged Iranian involvement in a suspected plot to assassinate the Saudi ambassador to the US.

Iran, where a judge on Monday reportedly sentenced to death a US-Iranian former Marine for "membership of the CIA", has also threatened to close the Strait of Hormuz, a chokepoint for 20 percent of the world's oil.

US Defense Secretary Leon Panetta warned on Sunday that any such move would cross a "red line" and "we would take action and reopen the strait."

Meanwhile Nuland condemned the death sentence handed to US-Iranian ex-Marine Amir Mirzai Hekmati in Iran and said allegations that he worked for the CIA were "false."

Iran's supreme leader Ayatollah Ali Khamenei said that Tehran will not bow to sanctions, in comments broadcast on state television on Monday.

After years of on-off efforts to end North Korea's nuclear program, the United States recently made a tactical shift to maintain low-level dialogue as a way to discourage future provocations even if no big issues are resolved.

But experts said that Kim Jong-Il's death fundamentally changes US calculations. Instead of a recalcitrant strongman, the United States now must deal with an untested young leader who remains a mystery on the global stage.

Kim Jong-Il, 69, had been groomed for 14 years as successor to his father, the regime's founder Kim Il-Sung. Heir apparent Kim Jong-Un is in his late 20s and is believed to lack a firm support base within the opaque regime.

North Korea expert L. Gordon Flake, executive director of the Mansfield Foundation, said that US diplomacy is dependent on policy, not personalities, but that Pyongyang is unlikely to be able to make key decisions right now.

But Flake, who advised then-senator Barack Obama during his presidential campaign, said the longer-term implications could be different. Kim Jong-Il set off repeated crises since inheriting power in 1994, including carrying out two tests of nuclear weapons.

"Some people thought for his entire reign that we're just waiting around the corner for Kim Jong-Il to be some type of reformer. That obviously didn't pan out," he said.

"In the short run, there is the risk that North Korea may lash out. But in the long run, I don't think there's any way to bemoan Kim Jong-Il's passing," he said.

US policymakers had hinted in recent weeks that they were making some headway with North Korea, which could perhaps open the way for more formal talks or a resumption of US food assistance to the impoverished state.

Secretary of State Hillary Clinton, who was due to meet Monday on potential food aid, instead huddled with aides over Kim's death. She urged a "peaceful and stable" transition and hoped for better relations with "the people of North Korea."

Obama's administration, despite its policy worldwide of not closing the door on talks with US adversaries, had been adamant that it will not resume formal negotiations until North Korea clearly commits to past agreements on denuclearization.

Bruce Klingner of the Heritage Foundation, a conservative think-tank, noted that "very few if any officials in the administration were optimistic" about North Korea after two deadly incidents against South Korea last year.

"The death of Kim Jong-Il would presumably delay a resumption of (US) negotiations as the new North Korean leadership assesses to what degree it is willing to open up to the outside world," Klingner said.

"Although the demise of Kim Jong-Il provides an opportunity for change on the Korean peninsula, it is a transition fraught with uncertainty, nervousness and potential danger," he said.

While Kim's death sent shockwaves throughout the world, the news was not unexpected. He suffered a stroke three years ago and, with his reputed passion for fatty foods and alcohol, was certainly not known for a healthy lifestyle.

In a presentation last year, a military strategist warned that the United States needed to study all possible outcomes as a complete collapse of the nuclear-armed regime could trigger a crisis unseen since World War II.

Colonel David Maxwell of the Army's Special Operations Command, who said he was speaking in personal capacity, said in the presentation that North Koreans should be expected to resist fiercely any foreign forces and could mount an insurgency far more sophisticated than those seen in Iraq or Afghanistan.

Former New Mexico governor Bill Richardson, who has maintained contacts with North Korea since his time as US ambassador to the United Nations, said that fellow Democrat Obama is "playing it correctly by playing it cool."

"You got to watch things in the next 48 hours. I think what the North Korean military commanders say in the next day or so is going to be critical," Richardson told CBS television.

Some members of the rival Republican Party urged regime change. Senator John McCain voiced satisfaction that Kim was "in a warm corner of hell" and, while urging caution, called for "determined and creative leadership" to end his regime.

Representative Ed Royce, a Republican who has led a push against US food assistance, said the transition "is less stable than may appear" as "the North Korean people are starting to question this corrupt dynasty."

"Now is not the time for talk of new beginnings and food aid. We should be doing what we can to delegitimize this succession with the suffering North Korean people," Royce said.

"Tests showed that the Sodium-22 could only have been obtained as the result of the work of a nuclear reactor," it said in a statement. "A criminal enquiry has been opened and the materials transferred to prosecutors."

Customs had been alerted by a warning system at Sheremetyevo airport ahead of the Moscow to Tehran flight that background radiation in the departures hall was 20 times the norm. A passenger's bag was then searched.

"Eighteen metallic objects of industrial origin were found, packed into individual steel boxes," it said.

"Tests then found that the objects were in fact the radioactive isotope Sodium-22 that had been machine-produced."

No further details were immediately available on the consignment or the identity of the passenger who was carrying the materials.

Spokesman for Russian state nuclear agency Rosatom Sergei Novikov said Sodium-22 was used for medical and research purposes and produced in so-called cyclotrons, a type of particle accelerator, and not in nuclear reactors.

"There are a lot of cyclotrons in Russia," he told AFP, adding that they were used in medical and educational establishments where security levels were not as tight as those at nuclear reactors.

Rosatom only supplies Iran with medical isotopes, molybdenum-99 and iodine-131, Novikov added, without providing further details.

Russia has relatively close ties with Iran and has built its first nuclear power station in the southern city of Bushehr. Moscow has also delivered the nuclear fuel for the reactor.

Moscow has echoed Western concerns about the nature of the Iranian nuclear programme but has stopped short of publicly accusing Tehran of seeking atomic weapons and always said that the standoff should be solved by diplomacy.

Experts have long called for tight controls against nuclear smuggling so Iran cannot get hold of materials it is barred from obtaining under UN Security Council sanctions.

Obama said the move by a country where he spent four years as a boy showed the "positive leadership role" that Indonesia could play in combating the spread of nuclear weapons.

"I urge all states to sign and ratify the agreement so that it can be brought into force at the earliest possible date," Obama said.

The president also said that he will continue to press the US Senate to ratify the treaty, which he said was important to future US security.

"America must lead the global effort to prevent proliferation, and adoption and early entry into force of the CTBT is a vital part of that effort," Obama said.

The Senate blocked ratification of the treaty in 1999 and it has still not been ratified, despite a pledge by the Obama administration to seek such a step.

Advocates say US ratification of the treaty would send an important signal to the rest of the world on the importance of checking nuclear proliferation.

But US critics of the treaty argue that by committing itself to a long-term binding pledge never to test nuclear weapons, the United States could undermine confidence in its atomic weapons arsenal.

US Secretary of State Hillary Clinton also praised Indonesia's move.

"The United States, which has observed a moratorium on nuclear explosive testing since 1992, is committed to the ratification of the Comprehensive Nuclear Test-Ban Treaty and to its early entry into force," she said.

"The United States calls on all governments to declare or reaffirm their commitment not to conduct explosive nuclear tests, and we urge all states that have not yet ratified the treaty to join us in this effort," Clinton said in a statement.

So far, the CTBT, which aims to outlaw all nuclear explosions, has been signed by 182 states but 44 key states -- all with nuclear technology -- need to ratify it before it can come into force.

With Indonesia's vote, 36 of these countries have now ratified the treaty.

But among those still missing are North Korea, Iran, Israel, Pakistan, India, China and the United States -- all states known to have or suspected of developing nuclear weapons.

"Our efforts and those of the world have failed to convince Israel to abandon its weapons of mass destruction, as well as Iran... therefore it is our duty towards our nation and people to consider all possible options, including the possession of these weapons," Faisal told a security forum in Riyadh.

"A (nuclear) disaster befalling one of us would affect us all," said Faisal.

Israel is widely held to possess hundreds of nuclear missiles, which it neither confirms nor denies, while the West accuses Iran of seeking an atomic bomb, a charge the Islamic republic rejects.

Riyadh, which has repeatedly voiced fears about the nuclear threat posed by Shiite-dominated Iran and denounced Israel's atomic capacity, has stepped up efforts to develop its own nuclear power for "peaceful use."

Abdul Ghani Malibari, coordinator at the Saudi civil nuclear agency, said in June that Riyadh plans to build 16 civilian nuclear reactors in the next two decades at a cost of 300 billion riyals ($80 billion).

He said the Sunni kingdom would launch an international invitation to tender for the reactors to be used in power generation and desalination in the desert kingdom.

The United Nations has imposed successive packages of sanctions against Tehran over its refusal to suspend uranium enrichment. Those measures have been backed up by unilateral Western sanctions.

Prime Minister Julia Gillard had pushed for the scrapping of the ban on exports to the nuclear power, which is not a signatory to the Nuclear Non-Proliferation Treaty, to help meet its energy needs.

"I'm very pleased with the decision," Smith told Sky News, adding that Australia's policy had been an "irritant" in the relationship.

"This will be a deeply significant decision so far as our strategic relationship with India is concerned," Smith said.

Australia's governing Labor party voted Sunday to lift the long-standing ban on exporting uranium to India after a passionate debate about nuclear weapons and reactor safety following Japan's quake crisis.

At the conference, Gillard said it was not rational or intellectually defensible to sell uranium to powers such as China but not India, "the world's largest democracy".

Canberra ships the nuclear fuel to China, Japan, Taiwan and the United States but has so far refused to sell to India because it is not a signatory to the non-proliferation treaty.

Any sales to India will instead be regulated by strict safeguards, which Canberra and New Delhi are expected to enter discussions on in 2012, Trade Minister Craig Emerson said.

"There's no doubt that India wants to use uranium for peaceful purposes," Emerson told ABC Radio.

"It's entered into agreements with other countries that confirm this."

Although Australia does not use nuclear power, it is the world's third-ranking uranium producer behind Kazakhstan and Canada and holds an estimated 23 percent of the world's reserves.

The Washington Post reported Tuesday that Georgetown University students under the instruction of a former Pentagon official have assembled the largest body of public knowledge yet about a vast network of secret tunnels dug by China's secretive Second Artillery Corps, responsible for nuclear warheads.

The 363-page study has not yet been published, but has already sparked a congressional hearing and been circulated among top US defense officials, including the Air Force vice chief of staff, the Post reported.

"Its not quite a bombshell, but those thoughts and estimates are being checked against what people think they know based on classified information," it quoted an unnamed Defense Department strategist as saying.

The newspaper said critics of the report had questioned the students methods, which included using Internet-based sources like Google Earth, blogs, military journals and even a fictionalized Chinese TV show.

But the Post also said the students were able to obtain a 400-page manual produced by the Second Artillery and usually only available to Chinese military personnel.

The students professor, Phillip Karber, 65, spent the Cold War as a top strategist reporting directly to the secretary of defense and the chairman of the Joint Chiefs of Staff, the Post said.

Karber said that -- based on the study of the tunnels -- China could have up to 3,000 nuclear warheads, far higher than the current estimates, which range from 80 to 400, according to the Post.

US officials could not immediately be reached to comment on the report.