At least 16 Iraqis have been killed in a U.S.-backed raid on a Shi'ite neighborhood near the Sadr City slum in northeast Baghdad.
Accounts of Sunday's raid vary.
The U.S. military says Iraqi special operations forces carried out the raid to disrupt a terrorist cell, noting that 16 "insurgents" were killed. But aides to radical Shi'ite cleric Moqtada al-Sadr accused U.S. troops of killing more than 20 innocent people at a mosque.
Coalition forces say no mosques were entered or damaged during the operation.
And Iraqi police say some 20 Shi'ite militiamen died in clashes sparked by a U.S.-raid on a mosque.
Elsewhere in the capital, Iraqi authorities say U.S. forces arrested 40 Iraqi security personnel after raiding a bunker where 17 foreigners were being held.
And Iraqi police say they found 30 decapitated bodies near the city of Baquba. The discovery is the latest since sectarian violence flared following the bombing of a Shi'ite shrine last month.
In other violence, a roadside bomb killed a teenage boy as he walked to school in Basra. A bomb in Baghdad killed a woman. And gunmen killed two people, including a police officer, near Baquba.
The attacks came as Iraq's Shi'ite, Sunni Arab and Kurdish leaders failed again to agree on a government, despite increasing U.S. pressure.
Some information for this report was provided by AFP, AP and Reuters.