Shi'ite cleric Moqtada Al-Sadr has threatened an "open war" against the Iraqi government unless it halted a crackdown by Iraqi and US security forces on his followers.

The spectre of a full-scale uprising by Sadr sharply raises the stakes in his confrontation with Prime Minister Nuri al-Maliki, who has threatened to ban the anti-American cleric's movement from political life unless he disbands his militia.

A rebellion by Sadr's Mehdi Army militia -- which has tens of thousands of fighters -- could abruptly end a period of lower violence at a time when US forces are starting to leave Iraq.

"I'm giving the last warning and the last word to the Iraqi government -- either it comes to its senses and takes the path of peace ... or it will be (seen as) the same as the previous government," Sadr said, referring to Saddam Hussein's fallen regime, without elaborating.

"If they don't come to their senses and curb the infiltrated militias, then we will declare an open war until liberation."    

Sadr's movement accuses other Shi'ite parties of getting their militias into the Iraqi security forces, especially in southern Shi'ite Iraq where various factions are competing for influence in a region home to most of Iraq's oil output.

Sadr launched two uprisings against US forces in 2004.

His movement then entered politics and backed Maliki's rise to power in 2006. But the youthful Sadr split with Maliki, a fellow Shi'ite, a year ago when the prime minister refused to set a timetable for the withdrawal of US troops from Iraq.

"Do you want a third uprising?" Sadr said, adding that he wanted Iraq's Shi'ite clerical establishment to set a date for the departure of American troops.

In Sadr's Baghdad stronghold of Sadr City, one Mehdi Army commander said he was "thrilled" about the statement.

"We will wait until tomorrow to see the response of the government. Otherwise they will see black days like they have never seen before in their life."    

Sadr's threat could not come at a worse time. On Friday, US forces said they had intelligence suggesting Sunni Islamist al Qaeda, pushed out of Baghdad and western Iraq last year, was plotting a return to the capital to stage major bomb attacks. - Reuters