In political developments, Sunni Arabs on the committee drafting a new constitution rejected Kurdish demands for federalism as long as foreign forces remain in Iraq. The statement came on the eve of a meeting to try to overcome differences on the charter.

Iraq's most feared terror group, meanwhile, warned Sunni Arabs that voting in a referendum on the charter this fall would be tantamount to rejecting Islam.

The fighting erupted about 8 p.m. Friday when guerrillas opened fire on an Iraqi army position, the American military said. U.S. attack helicopters responded with rockets and gunfire.

At nearly the same time, a suicide attacker drove a truck loaded with explosives into a nearby Iraqi army checkpoint, killing an Iraqi soldier. A second suicide driver tried to attack another Iraq position in the area, but a U.S. tank opened fire and the car detonated prematurely.

Minutes later, insurgents at a fourth location fired two rocket-propelled grenades and a mortar round at another Iraqi army post in southern Baghdad. None of the rounds caused any damage, the U.S. statement said.

Over the next two hours, insurgents tried to launch further attacks on the two Iraqi army posts but were driven off by U.S. and Iraqi fire, the statement added.

U.S. troops suffered no casualties, but six insurgents were killed and 12 were captured in the fighting, according to the military. Separately, the U.S. command said an American soldier assigned to a unit in the northern city of Mosul was killed in action Thursday ''during a terrorist attack'' there. No further details were given.