BAGHDAD, Iraq -- U.S.-led forces reported killing 49 insurgents on Sunday during predawn clashes with renegade Shiite militia members.
The fighting was the deadliest in recent months and further stoked furor among Iraqis over the heavy toll the war is taking on civilians.
The U.S. military claimed that no civilians were killed or injured during the raid, while Iraqi police said at least 13 were dead, including three children and a woman. Iraqi authorities said 69 people were injured.
The U.S. military could not account for the differing tally of casualties.
Television news broadcast images of caskets and grieving families in the streets of Sadr City.
The gun battles erupted after armored military vehicles, backed by helicopter gunners, arrived on the fringes of Sadr City to conduct a door-to-door sweep for a rogue militia cell leader the United States accuses of masterminding the kidnapping of coalition soldiers and other foreign nationals in May and last November.
The target of the manhunt was neither captured nor killed, the military said.
"It's the biggest raid in two months," said Karem Hellal, 45, who was out on the street when the soldiers descended on his neighborhood.
In August, the U.S. military reported killing 32 suspected insurgents during air strikes in Sadr City.
Hellal said gunfire killed a neighbor's 6-year-old child and seriously wounded the same neighbor's 2-year-old son.
Sirens wailed as ambulances carried the injured to the hospital. Doctors treated casualties, including children, at Imam Ali hospital, the biggest in Sadr City.
Prime Minister Nouri al Maliki expressed his concerns about the raid during a meeting with U.S. Gen. David Petraeus, who leads the coalition forces in Iraq.
In a statement released by the prime minister's office, Maliki vowed an investigation into Sunday's military action in Sadr City. He called for better coordination of military offenses with Iraqi troops to "avoid such regrettable incidents," the statement said.
In an interview on CNN, Iraqi government spokesman Ali al-Dabbagh underscored the brewing tensions. He condemned Sunday's offensive as "excessive."
"It is not creating a good atmosphere," he said. "We have today, again, one more problem created."
In the interview, Al-Dabbagh added that "there is a great anger in the country in Baghdad against killing such civilians, 49 civilians being killed until now."
The U.S. military stood by assertions that civilians were neither killed nor wounded.
"Coalition forces only engage hostile threats and make every effort to protect innocent civilians," said Maj. Winfield Danielson, a spokesman for the U.S.-led coalition forces in Iraq.
Sunday's deaths in Sadr City could add to inflamed passions among Iraqis against the American presence. Emotions are still raw over the Sept. 16 shooting deaths of 11 Iraqi civilians by employees of Blackwater USA, a private security firm hired by the U.S. State Department to protect diplomats.
The website iraqbodycount.org estimates civilian deaths could now exceed 82,200 since the start of war in 2003.
The military said it had returned fire from a volley of machine guns and rocket-propelled grenades in at least three separate gun battles in several Sadr City neighborhoods.
"They engaged us on the way in and on the way out," Danielson said.
Ground forces were attempting to clear several buildings when they were fired upon from nearby structures, the military said. A roadside bomb detonated as U.S. troops left, but there were apparently no casualties, the military said.
The raid lasted more than three hours, witnesses said, in a predominantly poor area on the fringes of Sadr City, a stronghold of Shiite militias mostly loyal to radical cleric Muqtada al-Sadr.
Sadr has called on militias loyal to him to refrain from attacks. In response, U.S. military officials have said they, too, would show restraint.
But Danielson, the military spokesman, said "we will not show the same restraint against those criminals who dishonor this pledge by attacking security forces and Iraqi citizens."
U.S. officials declined to name the target of Sunday's sweep, who they said has sought to carry out high-profile kidnappings and has ties with the Iranian Revolutionary Guard's Quds Force. The United States has accused Iran of funding and supplying Iraq's Shiite militias.
In a statement during a session of parliament, Falah Shanshal, a prominent member of the Sadr bloc of parliament, condemned Sunday's raid. He called the offensive an "inhumane crime" that adds to the "chaos and instability" in Iraq.
McClatchy special correspondents Jenan Hussein and Mohammed Al Dulaimy contributed to this report.