British and French ships joined a US carrier group in a six-strong flotilla of warships which passed through the sensitive Strait of Hormuz, Britain’s Ministry of Defence said.

The ministry said a Royal Navy frigate, HMS Argyll, was part of a US-led carrier group to sail through the waterway which Iran has threatened to close over Western moves to impose new sanctions over Tehran’s nuclear programme.

A spokesman said: “HMS Argyll and a French vessel joined a US carrier group transiting through the Strait of Hormuz, to underline the unwavering international commitment to maintaining rights of passage under international law.”

He said Britain maintained “a constant presence in the region as part of our enduring contribution to Gulf security”.

British warships have been patrolling in the Gulf continuously since the 1980s.

The US aircraft carrier USS Abraham Lincoln on Sunday passed through the Strait and is now in the Gulf, the Pentagon said.

“USS Abraham Lincoln … completed a regular and routine transit of the Strait of Hormuz… to conduct maritime security operations as scheduled,” Pentagon spokesman Navy Captain John Kirby said in an email to AFP.

“The transit was completed as previously scheduled and without incident.”

The carrier, which can have up to 80 planes and helicopters on board, was escorted by the guided-missile cruiser USS Cape St George and two destroyers.

While allied ships often participate in US naval exercises and sometimes are part of joint naval flotillas, the presence of British and French ships seemed to be a message to Tehran about the West’s resolve to keep the route open.

Iran’s military and political leaders had warned they could close the strait — a key transit route for global oil supplies — if increased Western sanctions over Tehran’s suspect nuclear program halt Iranian oil exports.

The Islamic republic’s navy had also warned it will react if the United States tried to redeploy one of its aircraft carriers to the waterway.

US Defense Secretary Leon Panetta has repeatedly said that closing the strait would cross a “red line.” Two of the 11 US aircraft carriers are currently in the region.

Since then, Iran has tried to ease tensions, with Foreign Minister Ali Akbar Salehi saying last week that Tehran had never tried to close the strait.

We want peace and stability in the region,” Salehi said.

European Union foreign ministers meeting in Brussels on Monday are expected to agree to sanction Iran’s central bank and announce an embargo on buying Iranian oil.

The United States, France, Britain and Germany accuse Iran of seeking to build a nuclear bomb, but Tehran says its nuclear drive is peaceful.