A "quiet" campaign to rein in the Shia militias in Iraq gathered pace today with the capture of two high-level commanders of the al-Mahdi Army.

US helicopters provided air cover as Iraqi security forces attacked a militia stronghold in the Sadr City slum this morning.

During a 43-minute gun battle, seven militiamen were killed and 34 wounded, according to a local hospital official, and a regional commander was taken prisoner.

The US army issued a statement saying that the captured commander was trying to set up a breakaway insurgent operation and was involved "in the transfer of weapons from Syria into Iraq". He was named by local people as Abu Diraa.

There were no casualties among coalition and Iraqi forces.

Today's raid in east Baghdad follows a similar joint swoop near the town of al-Hillah early today, when US and Iraqi forces picked up Adnan al-Unaybi, the commander of the al-Mehdi army south of Baghdad.

The al-Mehdi army, affiliated to the influential Shia cleric Hojetoleslam Moqtada al-Sadr, has been linked to a range of atrocities.

The militia is believed to be behind the majority of the tortured and mutilated corpses of kidnapped Sunnis found dumped in Baghdad each month, with holes drilled in their eyes and arms. It is also alleged to have carried out the kidnap last Sunday of Tayseer al-Mashhadani, a Sunni woman MP, which prompted other Sunni MPs to withdraw from parliament in protest.

The violence perpetrated by the Shia militias against Sunni civilians, like the atrocities carried out by Sunni insurgents, are one of the main impetuses driving Iraq in the direction of sectarian civil war.

Political will to tackle the Shia militias - who have also infiltrated the police in Baghdad and Basra - was previously perceived to be weak. Ibrahim al-Jaafari, the previous Prime Minister, was close to Hojetoleslam al-Sadr and also to the government in Iran, which is believed to be secretly arming fundamentalist Shias in Iraq.

Nouri al-Maliki, the Prime Minister who heads the new coalition government, is also a Shia Muslim but has signalled his determination to tackle the men of violence. He has said that militias should gradually be disbanded and melded into Iraq’s security forces.

"It is evident that the new government and the Americans are now trying to tackle the militias," said Ned Parker, Times Correspondent in Baghdad.

"In the last month there has been a quiet campaign to try to crack down. There have been a few raids like this in the last month.

"The Mehdi army is maybe the group that is most out of control in Baghdad at the moment, but they have links to people in government so no-one is entirely sure how to deal with it."

Coalition sources say that the al-Mehdi army's unsavoury reputation may be becoming an embarrassment to Hojetoleslam al-Sadr.

"We have been told that it is possible that al-Sadr is allowing these raids to happen because there are people around him that he himself sees as trouble, and who are a growing embarrassment to him," added Parker.

"I should stress that that was speculation from a coalition military official."

A spokesman for Hojetoleslam al-Sadr put out a statement condemning this morning's raid, claiming that 11 civilians were killed and dozens wounded as US jets fired into the densely packed residential area as people slept on their roof terraces to evade the searing summer heat inside their homes. Electricity blackouts make it impossible to keep houses cool with air conditioning.

"This is a big escalation from the Americans," said Sheikh Abdul-Hadi al-Darraji, an al-Sadr aide. "I condemn all the silence towards such violations and I call for the withdrawal of the American forces."

A police spokesman in Sadr City put the number of dead at nine, and said that one was a woman.

The US Army statements on this morning's raids stressed the determination to clamp down on suspected "anti-Iraqi forces", and described the activities of the militia leaders.

"The captured individual (in Sadr City) heads multiple insurgent cells in Baghdad whose main focus is to conduct attacks against Iraqi and coalition forces. These attacks include the use of Improvised Explosive Devices, or IEDs, and vehicle-borne IEDs," said the US statement.

"He and his followers have kidnapped, tortured and murdered Iraqi citizens, and he is also is personally responsible for the killing two Iraqi soldiers in an attempt to improve his organisation’s status with higher leadership. Additionally, he is linked to a 'punishment committee' that carries out vigilante judgment on perceived enemies of his organisation.

"This individual is also involved in the transfer of weapons from Syria into Iraq to reportedly facilitate his efforts to splinter away from his current insurgent organisation."

Al-Unaybi, the militia leader picked up in al-Hillah, had previously been arrested for a campaign to impose fundamentalist values, including "assaulting innocent Iraqi men and women, burning down liquor stores, and tearing down public billboards of famous Iraqi singers", the US said.

"Adnan Al-Unaybi, commander of the Jash Al Mahdi Euphrates Corps, was taken into custody at his home around 5:45 a.m. in a cordon and search mission in connection with terrorist activities in the northern Babil province.

"There were no shots fired and no injuries during the capture and detention. A Glock G19, cell phone and documents were found and confiscated during the search. Through Prime Minister Nouri Kamil al-Maliki’s intent to eradicate terrorism in Iraq, the elite Iraqi policemen of the Ministry of Interior cordoned the residence of Unaybi and detained him for leading a terrorist militia network in the town of al-Mahawil, near Al Hillah."

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