Shi'ite Muslim cleric Moqtada al-Sadr, who led revolts against US forces in Iraq before their pullout and became a major influence in the government, said he is leaving political life and has dissolved his movement.

Sadr gave no reason for the retirement announced via a handwritten statement on his website.

But two members of his political bloc Ahrar, which holds roughly an eighth of the seats in parliament, said he was angry after they defied his orders by voting in favor of a controversial bill that guarantees legislators high pensions.

"I announce my non-interference in the political affairs in general and there is no bloc representing us anymore, or any position inside or outside the government, or in parliament," Sadr said in the statement posted on Saturday evening.

"Everyone who infringes upon this will be exposed to religious and legal responsibility."

According to the statement, charitable and educational organisations run by Sadr will remain open.

Sadr spearheaded militant uprisings against US forces before their withdrawal in December 2011 and became a powerful presence in government after his bloc's backing for Shi'ite Prime Minister Nuri al-Maliki helped secure his position.

But the two later fell out, with Sadr criticising Maliki for amassing too much power, and analysts said his withdrawal from politics could work in favour of the premier.

It is not clear what impact Sadr's decision would have on his bloc's participation in parliamentary elections scheduled for April.

"Sadr's decision will definitely play into the hands of Prime Minister Maliki in the next election in one way or another," said Ali Ameer, an analyst specialising in Shi'ite religious affairs.-Reuters