NAJAF, Iraq (AFP) - Firebrand Shi'ite cleric Moqtada al-Sadr, leader of a powerful political movement and a major figure in the formation of post-Saddam Iraq, has announced his exit from politics two months before legislative polls.

"I announce my non-intervention in all political affairs and that there is no bloc that represents us from now on, nor any position inside or outside the government nor parliament," Mr Sadr said in a written statement received by AFP on Sunday.

Mr Sadr's group currently holds six Cabinet posts as well as 40 seats in the 325-member parliament.

He also said his movement's political offices will be closed, but that others related to social welfare, media and education will remain open.

It was not immediately clear if the decision was temporary or permanent, with Sadrist officials surprised by the announcement not in a position to clarify.

One official from Mr Sadr's office told AFP that no one wanted to discuss the issue "because it was a surprise decision".

"I do not think it will be reversed... because it is a very strong decision," the official added however.

If confirmed as permanent, Mr Sadr's announcement brings to a close a political career spanning more than a decade.

It began with his sharp criticism of the 2003 US-led invasion of Iraq, with his movement subsequently gaining seats in parliament, Cabinet posts and playing the role of political kingmaker.

Mr Sadr's widely-feared Mahdi Army militia also repeatedly battled American forces, and played a major role in the brutal sectarian conflict between Iraqi Sunnis and Shiites in which tens of thousands of people died.

Mr Sadr suspended the militia's activities in 2008 following major battles with Iraqi and US security forces.

Mr Sadr said the decision to leave politics was taken from the standpoint of Islamic law and of "preserving the honourable reputation of Sadr, especially of the two Sadr martyrs," referring to his father and another relative who were killed during Saddam Hussein's rule.

The move also aims to "end all the corruptions that occurred or which are likely to occur" that would harm the Sadr reputation, he said.