Mr Sadr, a firebrand whose militia has fought US forces since March, called for a new start and an end to conflict, according to witnesses.

But his supporters clashed with members of a pro-US faction in nearby Najaf.

Stones and shoes were thrown in the clash at the shrine of Imam Ali leaving several people injured and forcing the cancellation of Friday prayers.

Mr Sadr called upon the interim government to work to end the occupation according to a timetable set by Iraqi officials, reported a correspondent for Voice of Mujahidin radio present at the sermon.

Mr Sadr added that the formation of the government was a good opportunity to bury past differences and "forge ahead toward the building of a unified Iraq".