US forces in Iraq have said they killed about 30 militants in an overnight raid in the Sadr City district of Baghdad. Witnesses say civilians, including women and children, also died.
The US military said its jets and helicopters fired at a group of armed men during an operation against militants accused of smuggling weapons into Iraq from Iran.
Sadr City is home to the Mahdi Army, whose members follow the radical Shia cleric, Moqtada Sadr.
A military spokesman said there had been women and children in the area during the raid, but denied any had been killed.
Later, hundreds of mourners marched through Sadr City in protest against the raid and subsequent air strikes.
The violence came after Iraqi authorities imposed a three-day driving curfew in Baghdad on the eve of a major Shia religious festival in the capital.