241 Pizza

Ominously, Harith al-Idhari, head of the Sadr office in Basra, said that the militants did not put up any resistance in observance of a ceasefire declared by the cleric last August.

After the 2004 uprisings, the political wing of the Sadr movement agreed to join the political process, helping Mr Maliki, also a Shia Arab, rise to power two years later. Last year, however, the youthful cleric withdrew his support from the Government after the Prime Minister refused to set a timetable for the exit of US troops from Iraq – his central demand.

Against a backdrop of escalating sectarian slaughter over the summer, Hojatoleslam al-Sadr also ordered his fighters to observe a six-month ceasefire, a command that was renewed in February but now looks on the brink of collapse.

"Do you want a third uprising?" the cleric’s statement said. It gave no indication as to how long the Government had to respond.

The rallying cry prompted mosques in Baghdad's Shia bastion of Sadr City to blare out a call to arms, residents said.

"Fight the occupiers - get them out of your homes," the late-night messages said. "They [the US] are calling for division. We demand that the siege of Sadr City be lifted."

Iraqi and US forces are constructing a wall to partition off the southern quarter of Sadr City, a teeming slum of some 2.5 million Shia Arabs as well as the Baghdad hub of the Mahdi Army.

Commanders say that the wall will help to protect civilians. Walls have been built elsewhere in the capital to contain the violence. Residents, however, argue that the concrete barriers give the impression of being in a prison.

“We have had great success in other parts of the city using concrete to provide a secure environment for the citizens and that’s really the major part of it,” said Brigadier-General Will Grimsley, deputy commander of US forces in Baghdad.

Iraqi forces, backed by US troops and air power, have been battling Mahdi Army fighters in Sadr City since the operation in Basra triggered a wave of unrest across the Shia south and up to the capital on March 25. In ongoing clashes overnight, the US military said it had killed seven “criminals” in Sadr City.

Away from the Shia strife, al-Qaeda in Iraq also appears to be gearing up for another offensive, with the purported leader calling for renewed attacks on US troops over the next month.

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