BAGHDAD, Iraq, (AP) -U.S. and Iraqi forces fought militiamen early Sunday in Diwaniyah, a southern city under the increasing influence of the Madhi Army loyal to radical Shiite cleric Muqtada al-Sadr. Twenty militia fighters were killed, the U.S. military said.

The clashes broke out after a joint U.S.-Iraqi unit raided the house of Kifah al-Greiti, a Mahdi Army commander, said Iraqi Army Capt. Fatiq Ayed.

Three teams of militiamen, armed with rocket-propelled grenades, opened fire on U.S. soldiers and damaged an M1A2 Abrams tank, the U.S. command said. No coalition forces were hurt.

“Iraqi army and (U.S.) soldiers engaged and killed 20 terrorists during the fighting,” the military said in a statement.

Fighting could be seen in two neighborhoods and heavy explosions could be heard through the night. An Associated Press reporter saw U.S. soldiers sealing off roads to the city after dawn in an apparent attempt to keep the insurgents from bringing reinforcements.

The fighting subsided later in the morning.

Diwaniyah, 80 miles south of Baghdad, was the scene of a fierce fight in August between the Mahdi Army and Iraqi forces that left 23 Iraqi troops and 50 militiamen dead and scores wounded.

Separately, the U.S. command said an American soldier was killed Saturday when insurgents attacked his patrol with small-arms fire northwest of Baghdad. The name of the soldier was withheld pending notification of next of kin.