Both areas - a bazaar in the eastern Baghdad neighborhood of Shaab and the farming town of Khalis in Diyala province - are populated predominantly by Shiites, and Iraqi government officials quickly blamed the Sunni insurgent group al-Qaeda in Iraq.The attacks followed two violent days of bombings and reprisal killings in the northern city of Tall Afar and threatened to increase the likelihood of a resurgence of open sectarian warfare despite the heightened U.S. military presence in Iraq.

The bombing in Shaab, which police said killed at least 60 people, took aim at the six-week-old Baghdad security plan, under which U.S. and Iraqi officials have sought to protect public marketplaces from such catastrophic attacks.