Iraqi Shia cleric Moqtada al-Sadr has announced his exit from politics.

The leader of a powerful political movement was also a commander of a once-feared militia, the Mahdi Army.

He had been a fierce critic of the US-led invasion in 2003.

"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 statement.

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.

Iraq is due to hold parliamentary elections in April.