US forces killed 49 people in fierce fighting with militants in Baghdad's Shia stronghold of Sadr City on Sunday during a raid targeting an Iranian-linked insurgent, the military said.
Medics at four hospitals confirmed 17 dead, including a boy and a girl, but US military spokesman Major Winfield Danielson told AFP there were no civilian casualties and no reports of American losses.
The US military said troops were drawn into fighting after they launched a raid to seize their high-value target in Sadr City, a poor part of the capital dominated by militia loyal to anti-American cleric Moqtada al-Sadr.
"The operation's objective was an individual reported to be a long-time Special Groups member specialising in kidnapping operations," a statement from the military said.
"Special Groups" is a US military term for what it says are secret Shia cells which wage acts of "terrorism" in Iraq with the financial and military backing of Iran's elite Revolutionary Guards units.
"Intelligence indicates he is a well-known cell leader and has previously sought funding from Iran to carry out high profile kidnappings," the statement said.
Danielson said the targeted individual had not been killed or captured during the clashes, which the military said erupted when troops were attacked by gunfire and rocket propelled grenades.
"Responding in self-defence, coalition forces engaged, killing an estimated 33 criminals," the statement said, adding that air support was then called in and killed another six. Ten more were killed as US forces withdrew, it said.
"I can say that we don't have any evidence of any civilians killed or wounded. Coalition forces only engage hostile threats and make every effort to protect innocent civilians," said Danielson.
Pictures taken by an AFP photographer as grieving relatives carried off the bodies of the dead for burial showed the body of a young boy in a coffin and several wounded people being treated by hospital emergency staff. The US military has regularly targeted Sadr's Mahdi Army, which it accuses of being involved in sectarian killings of Sunnis.
Sadr declared a six-month freeze on the activities of his militia in August, including a halt to attacks on US-led coalition troops in Iraq.
US forces welcomed the freeze but continue to target fighters who it says have broken away from the main force of the Mahdi Army and formed special groups allegedly aided by Iran.
"We continue to support the government of Iraq in welcoming the commitment by Moqtada al-Sadr to stop attacks and we will continue to show restraint in dealing with those who honour his pledge," the military statement said. "We will not show the same restraint against those criminals who dishonour this pledge by attacking security forces and Iraqi citizens," said Danielson.