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Iraqi and US forces have captured more than 600 fighters loyal to firebrand Shiite cleric Moqtada al-Sadr, the US military said, while violence across the country claimed another 36 lives.
The arrest of Sadr's militiamen came after a day of carnage that left 100 people dead in a string of bombings in and around Baghdad.
A US defence official, meanwhile, said a helicopter owned by the US security firm Blackwater USA crashed in Baghdad Tuesday, killing five people.
“A quick reaction force and Blackwater employees went to the crash scene and found the remains of five people,” said the official.
The identity or nationality of the five was not immediately known nor was the cause of the accident.
Pan-Arab television network Al-Jazeera earlier said a helicopter had been shot down in the capital.
The crash comes just days after 13 US troops were killed in the crash of a UH-60 Black Hawk helicopter Saturday northeast of Baghdad, which officials believe may have been shot down with a shoulder-fired surface to air missile.
In a major crackdown launched in the past few weeks against the Mahdi Army — the militia headed by Sadr and now considered the biggest security threat to Iraq by the Pentagon — more than 600 fighters and 16 militia leaders have been detained, the military said.
“There are currently over 600 illegal Jaish al-Mahdi (JAM) militia in detention awaiting prosecution from the government of Iraq,” a statement said.
It said Iraqi and US forces had also detained 16 high-level militiamen and killed one commander in a series of operations against the Mahdi Army, known for its fierce anti-US stance.
“The detainees are responsible for attacks against the government of Iraq, Iraqi citizens and coalition forces,” the military said.
Combined Iraqi and US forces have carried out 52 operations in the past 45 days focused on the Mahdi Army as well as 42 operations that targetted Sunni extremists, it said.
The operations against Sunni extremists led to the capture of 33 cell leaders in Baghdad, the statement said, charging that the detainees were mainly involved in facilitating the entry of foreign fighters into Iraq.
The US military has accused the Mahdi Army, which is believed to have up to 60,000 fighters, of being heavily involved in the sectarian killing of Sunni Arabs in Baghdad and other regions of the country.
US and Iraqi forces aim to take down these fighters as part of a Baghdad security plan announced by US President George W. Bush earlier this month to crush the sectarian fighting that killed tens of thousands of people last year.
On Friday, security forces announced the capture of top Sadr aide Sheikh Abdul Hadi al-Darraji, a spokesman for the group in Baghdad, in a raid on a religious site in the Shiite slum district of Sadr City.
Before joining Iraq's political process, Sadr led two bloody rebellions against US forces in April and August 2004, a year after the US-led invasion to topple Saddam Hussein.
Mahdi fighters suffered heavy casualties in battles fought in the Shiite holy city of Najaf, after which Sadr joined Iraq's political process and emerged as a powerbroker in the current Shiite-dominated parliament.
He commands a group of 32 MPs in the 275-member parliament and six ministers in Prime Minister Nuri al-Maliki's embattled cabinet.
But fearing a sustained US planned assault, his political group on Sunday ended their nearly two-month long boycott of the government and parliament.
A source close to the Sadr movement told AFP Monday that the group had been told not to confront the Americans.
Insurgent attacks continued in Iraq, meanwhile, with at least 14 more people killed, including five policemen in the northern city of Mosul.
Police also recovered 17 corpses in Baghdad of men shot dead execution-style, a security official said.
US military and private security helicopters could be seen Tuesday circling over Baghdad's Sunni district of Adhamiyah, where an operation aimed at targeting militants was launched the previous day.
Three more US soldiers were reported dead on Tuesday, taking total deaths this month to 50 and the military's losses since the 2003 invasion to 3,056, according to an AFP count based on Pentagon figures.
