The US military says American and Iraqi forces have killed at least 30 suspected Shi'ite militiamen in the southern city of Diwaniyah.
Military officials say fierce fighting erupted Saturday night, when troops raided the house of a suspected local commander of the Mahdi Army, a militia loyal to Shi'ite cleric Moqtada al-Sadr.
An American tank was heavily damaged in the clashes, which continued over night and into Sunday. Military officials said four militants were captured in the operation, including one allegedly involved in the August murder of an Iraqi soldier.
Diwaniyah was also the scene of fierce fighting in August.
Elsewhere in Iraq, two U.S. soldiers were killed in separate incidents Saturday. In Baghdad, insurgents fired on a patrol, killing on U.S. soldier. In the northern city of Mosul, another soldier was killed by a roadside bomb.
In northern Iraq, security forces have begun a major crackdown in Kirkuk in an effort to stem a recent wave of violence.
Thousands of police and soldiers swept through neighborhoods in the city Saturday. Iraqi police say at least 150 suspected insurgents were detained and hundreds of weapons confiscated.
The mainly Kurdish city of Kirkuk, a major oil center, is the focus of a power struggle among ethnic factions.