"The six ministries shall be handed over to the government itself, hoping that this government would give these responsibilities to independent bodies who wish to serve the interests of the people and the country."
The Sadrists blamed the decision on Maliki's adamancy to set a timetable for the pullout of US-led occupation troops.
"The main reasons are the prime minister's lack of response to the demands of nearly one million people in Najaf asking for the withdrawal of US forces and the deterioration in security and services."
Marking the fourth anniversary of Baghdad's fall, hundreds of thousands of Iraqis took to the streets, demanding the pullout of occupation forces.
Maliki has steadfastly refused to offer any timetable, arguing that the departure of the US-led forces would be guided by the security situation on the ground.
The Sadrists form the biggest single political group in Maliki's cracking coalition with six ministries and a quarter of the parliamentary seats.
The Shiite Fadihla party withdrew from the ruling Shiite parliamentary bloc in March, accusing Maliki's government of pursuing a "sectarian" agenda.
Analysts believe the withdrawal of the Sadr bloc from the government was likely to be both a blessing and a concern for Maliki.
They argue that the move would give the prime minister greater freedom to pursue his policies.
However, there will be fears about keeping the Shiite leader engaged in the political process.
The International Crisis Group's Iraq expert Joost Hiltermann said Sadr was gambling on being able to wait out his US foes.
"Sadr does not want to restart fight with the Americans as there is a feeling that they will go away next year," Hiltermann told AFP.
"He wants to wait it out. But he has to consolidate himself," he added.
"This is an internal debate within the Sadr movement. Sadr wants to consolidate his ranks. His decisions are being challenged by his own people," argued Hiltermann.
"Sadr continues to be strong. He is the only popular movement in Iraq. He is going through difficult times as he has a loosely managed organization which is not disciplined."
Tareq Harb, a political analyst, said Maliki will use Sadr's withdrawal and the threat of a radical opposition to extract more aid from the United States.
"He will use this to exert pressure on the Americans to prepare for their withdrawal and intensify the training of the Iraqi troops."
The US has deployed thousands of additional troops in Baghdad in an effort to break the cycle of violence in the inflammable capital.
There have been clashes between fighters from Sadr's Mahdi Army militia and Shiite-led security forces since the launch of the Baghdad security plan.
Four years since the 2003 US invasion, Iraq is gripped by a bloody cycle of violence, killing at least 100 people on a daily basis.Güncelleme Tarihi: 17 Nisan 2007, 16:09