At least 10 people have been killed in crossfire between US troops and Iraqi Shia fighters in Baghdad's Sadr City district, while a blast elsewhere has killed four US soldiers.
The clashes in Sadr City early on Sunday came a day after a US rocket attack damaged a hospital in the stronghold of Muqtada al-Sadr, the Shia leader.
Iraqi security officials and medical sources said another 17 people were also wounded in the fighting in Sadr City.
There was no immediate word from the US military.