BAGHDAD, Iraq — American and Iraqi forces clashed with Shiite militiamen yesterday in the southern city of Diwaniyah after a raid on the home of a leader of the Mahdi Army, accused of killing Sunnis in Iraq’s spiral of sectarian violence.

The American military said 30 militiamen were killed in the fighting, which came about two months after a similar battle in the predominantly Shiite city, 80 miles south of Baghdad. Officials from the party of radical Shiite cleric Moqtada al-Sadr, which heads the militia, denied any of their fighters were killed.

An American Abrams tank was seriously damaged when it was hammered by rocket-propelled grenades, but no casualties were reported among the American or Iraqi forces.

American troops have been stepping up pressure on the Mahdi Army in past weeks, launching raids on the militia’s members and leaders in Baghdad and elsewhere as part of an intensified sweep in the capital aimed at reducing mounting bloodshed.

The American command also announced the deaths of two more soldiers, both killed Saturday. One died when insurgents attacked his patrol northwest of Baghdad, while the other was killed by a roadside bomb, the military said without specifying where the attack took place.

The deaths brought to 26 the number of Americans killed in Iraq this month — at least 16 of them in Baghdad amid the district-by-district crackdown.