Blasts kill four U.S. troops in northern Iraq

BAGHDAD (Reuters) - Two roadside bomb attacks killed four U.S. soldiers in northern and central Iraq on Tuesday, the U.S. military said, an unusually bloody day for American soldiers as they curtail their military activities.

In volatile northern Iraq, three soldiers were killed when a roadside bomb exploded near an American patrol, the military said in a statement, giving no further details. The statement did not say where exactly the attack had taken place.

Earlier in the day, another U.S. service member was killed by a roadside bomb in southern Baghdad, the military said.

Monthly death tolls for U.S. soldiers are at their lowest levels since the 2003 invasion, owing partially to sharply reduced U.S. military activity after the withdrawal of combat forces from Iraqi cities at the end of June.

U.S. forces must pull out of Iraq completely by 2012 under a bilateral security pact.

Violence has also dropped sharply across Iraq from the peak of the sectarian slaughter in 2006 and 2007, but a series of bomb attacks in recent months has raised doubts about abilities of Iraqi forces acting for the first time on their own.

August was the worst month for civilian casualties in Iraq since April.

Last month, four U.S. troops were killed in violence. More than 4,300 U.S. troops have died in Iraq since the 2003 U.S.-led invasion to oust Saddam Hussein, official figures show.

(Reporting by Tim Cocks; Editing by Jon Boyle)