Twelve people died in overnight clashes in Baghdad's Sadr City district, which has become a chief battleground between U.S. and Iraqi forces and the Mahdi Army of anti-American cleric Muqtada al-Sadr, police and hospital officials said Saturday.
Iraqi troops also kept up the pressure on Shiite militants in the southern city of Basra, where they fanned out through a Mahdi Army stronghold.
In Sadr City's general hospital, officials said 71 people were admitted for treatment of injuries received in the fighting. The hospital also received 12 bodies, said an official who asked not to be identified because he was not authorized to release the information.
The fighting came amid reports that Iraqi troops backed up by U.S. forces were trying to recapture a position in the district abandoned a day ago by a company of government soldiers.
Security forces in the area also have come under repeated attack by militants trying to prevent the construction of a concrete wall through the district.
The wall — a concrete barrier of varying height up to about 12 feet — is being built along a main street dividing the southern portion of Sadr City from the northern, where Mahdi Army fighters are concentrated.
American commanders hope that construction of the Sadr City wall, which began Tuesday, will hamper their ability to fire rockets and mortars at the Green Zone, the central Baghdad district where government offices and the U.S. Embassy are located.
The zone has been regularly shelled since the Iraqi military launched an operation against Shiite militias in Basra on March 25. That operation quickly stalled amid fierce resistance from the militants and mass desertions from the security forces.
But near-daily clashes in Sadr City since then have fueled worries over a total breakdown of a truce called last year by Muqtada al-Sadr, with fears of wider violence.
The government of Prime Minister Nouri al-Maliki also kept up the pressure on al-Sadr's followers in Basra, launching an operation early Saturday aimed at clearing militants from the Hayaniyah district, a Mahdi Army stronghold in Iraq's oil capital.
British artillery and U.S. warplanes were supporting the Iraqi army operation, which met minimal resistance, military spokesman Maj. Tom Holloway said.
He said that as a show of force British gunners fired a barrage of shells into an empty area near Hayanihah and U.S. warplanes bombed it.
"This was intended to demonstrate the firepower available to the Iraqi forces," Holloway said.
Meanwhile, the U.S. military said an American soldier was killed by a roadside bomb while on patrol in Salahuddin province. The statement raised to at least 4,038 members of the U.S. military who have died since the war started in March 2003 according to an Associated Press count.