Separately, the U.S. military says it is checking reports of an American helicopter crash south of Baghdad.

Witnesses said gunmen opened fire on the helicopter as it flew over the town of Latifiyah, about 35-kilometers south of the Iraqi capital - an area known to be a Sunni insurgent stronghold.

There was no immediate word about casualties.

Meanwhile, the U.S. military said coalition forces captured 17 suspected terrorists during raids in southwest Baghdad and the town of Karmah Thursday.

The military also said American and Iraqi troops detained two suspects in connection with last week's truck bombing in the northern town of Tal Afar that killed more than 100 people.

The truck bombing in a Shi'ite district of Tal Afar triggered a reprisal shooting spree by Shi'ite police and gunmen in a Sunni district of the town that killed nearly 50 people.

Separately, U.S. Army officials say two soldiers killed in Iraq's volatile al-Anbar province in February may have died as a result of friendly fire. The families of the two soldiers were initially told they were killed by enemy fire.

The army says it is investigating the deaths of the two soldiers. - VOA News