i told AFP from the movement's headquarters in the Shiite holy city of Najaf.

Sadr MP Gufran Saad said the movement was quitting the alliance because it was no longer being consulted about key decisions.

"There are reasons for our withdrawal from the Shiite alliance. The alliance has been taking decisions single-handedly without reverting to the member blocs," Saad said.

The United Iraqi Alliance (UIA) initially comprised four key Shiite factions - the Sadr group, the Supreme Iraqi Islamic Council of Iraq (SIIC), the Dawa party and the Fadhila party - and held 130 of the 275 seats in parliament.

However, the number dropped to 115 when the Fadhila party pulled out in March.

The Sadr bloc has 32 seats in parliament.

Obeidi last week told AFP the Sadrists were considering withdrawing from the bloc because the SIIC and Prime Minister Nuri al-Maliki's Dawa had formed another alliance with two Kurdish groups.

"On the one hand they are taking decisions in the bloc, but on the other hand they are plotting another alliance," said Obeidi.

Under pressure from Washington to bridge the sectarian divide, Maliki and leaders of his Dawa party on August 27 squeezed out a broadbrush deal with two Kurdish groups and SIIC.

They agreed to ease restrictions on former members of Saddam's Baath party taking up government jobs, to hold provincial elections - a key demand of Washington - and to help the security forces to rein in sectarian unrest.

Sadr MP Saad complained that his group had not been included in the negotiations.

"The Sadrist bloc had no information about the new alliance ... they do many things without reverting to the blocs," Saad said.

The Sadr group has already withdrawn its six ministers from Maliki's government, saying Baghdad had failed to provide basic services to the people.

On Saturday, Obeidi said the Sadrists were now planning to negotiate with the Fadhila party for a possible "future together."

When it pulled its MPs out of the main Shiite bloc six months ago, the Fadhila party accused its allies of sectarianism and said the division of Iraq's parties into opposing blocs based on religion had worsened relations between Sunnis and Shiites.

Iraq's fractious government is made up of ministers from both sides of the sectarian divide but there are frequent rows between Sunni and Shiite leaders and it has difficulty governing.

Maliki has said he will announce a cabinet reshuffle but has so far not been able to fill the vacant seats left by the Sunni and Shiite ministers.

He is currently running the government with 23 ministers out of an original 40.

The decision to pull out of the Shiite alliance will paralyse Maliki further, said Kurdish lawmaker Mahmud Othman.

"The government is on a shaky ground. If somebody moves a no-confidence motion in the parliament then we will know who has how much support," Othman told AFP.

With the Sadr pullout, Maliki's government can only count on the support of 136 lawmakers, including 53 from two Kurdish groups. If the Sadr bloc votes against him, it would bring the numbers of MPs who oppose him to 127. The other 12 MPs represent various small parties and could vote either way.

Othman said, however, groups opposing the government are themselves not united.

"There is no agreement within the government as well as within the opposition. Maliki is surviving because there is no alternative. Even the Americans say that," Othman said.

Among the opponents of Maliki is the Sunni National Concord Front which has regularly accused the Sadr movement of killing Sunni Arabs in the ongoing sectarian warfare.

Political analyst Said Abu Rish, author of a number of books on Iraq, believes Maliki's days as prime minister are numbered.

"Maliki is a dead duck," Abu Rish told AFP. "The Shiites won't accept him. He has nothing."