Iraqi authorities say a suicide car bombing in the northern city of Mosul has killed nine people.

Police say the attacker Tuesday blew up his vehicle outside the offices of the Kurdish political party the Patriotic Union of Kurdistan led by Iraqi President Jalal Talabani.

To the south, at least six people were killed in clashes between supporters of an anti-American Shi'ite cleric - Mahmoud al-Hassani - and Iraqi troops in the Shi'ite holy city of Karbala.

Meanwhile, the U.S. military has acknowledged that car bombs triggered the explosions that killed at least 63 Iraqis Sunday in Baghdad. The military says the blasts ruptured a gas line causing a residential building to collapse.

On Monday, U.S. Major General William Caldwell said explosives experts found no evidence of anything other than a gas explosion.

In Baghdad, the U.S. military says coalition forces have sealed off the capital's violent Dura district. The move is part of a broader push to stem rising sectarian violence.