Anti-American Iraqi Shi'ite cleric Moqtada al-Sadr has made his first public appearance since the start of a major US-backed security crackdown in February.
The radical cleric attended Friday prayers at a mosque in the southern city of Kufa and delivered an anti-American sermon, telling worshippers that occupation forces should leave Iraq.
US military officials say Sadr recently returned to southern Iraq after four months of hiding in Iran. His followers say the cleric never left Iraq.
Later Friday, Iraqi police said Abu Qadr, the leader of Sadr's Mahdi Army militia in the southern city of Basra, was killed in a clash with Iraqi and British forces.
In the latest US casualties, the military announced the deaths of six American soldiers, who were killed in roadside bombings and gun battles across Iraq.
Separately, the military says US and Iraqi forces raided Baghdad's mainly Shi'ite Sadr City neighborhood early Friday and detained a suspect linked to the leader of a terrorist cell.
Meanwhile, thousands of American and Iraqi troops are continuing their search for two of three US soldiers believed captured two weeks ago south of Baghdad by an al-Qaida-linked terrorist group.
The body of the third soldier was pulled from the Euphrates River Wednesday. He has been identified as Private First Class Joseph Anzack Jr.from Torrance, California.