BAGHDAD - A roadside bomb killed an American soldier in Baghdad on Saturday, capping the bloodiest week for U.S. troops in Iraq this year. Clashes persisted in Shiite areas, even as the biggest Shiite militia sought to rein in its fighters.
At least 13 Shiite militants were killed in the latest clashes in Baghdad's militia stronghold of Sadr City, the U.S. military said. Iraqi police said seven civilians also died in fighting, which erupted Friday night and tapered off Saturday.
The U.S. military said the American soldier was killed in a blast Saturday morning in northwestern Baghdad but did not say whether Shiite militiamen were responsible.
The death raised to at least 19 the number of American troopers killed in Iraq since last Sunday.
American casualties have risen with an outbreak of fighting in Baghdad between U.S. and Iraqi forces and the largest Shiite militia — the Mahdi Army of anti-American cleric Muqtada al-Sadr.
Al-Sadr, who is believed to be in Iran, repeated on Saturday his demand for American soldiers to leave the country and urged his fighters not to target fellow Iraqis "unless they are helping the (U.S.) occupation."
Al-Sadr also blamed the Americans and their Iraqi allies for the assassination Friday of one of his top aides, Riyadh al-Nouri, director of his office in the Shiite holy city of Najaf.
Gunmen ambushed al-Nouri as he was returning home from Friday prayers, and al-Sadr followers shouted anti-American slogans at his funeral in Najaf.
Despite the strident rhetoric, however, there were signs that al-Sadr was trying to calm his militia to avoid all-out war with the Americans. Al-Sadr is also under pressure from Prime Minister Nouri al-Maliki, also a Shiite, to disband the Mahdi Army or face a ban from politics.
Sadrist officials told The Associated Press they had received orders from their headquarters in Najaf to avoid confrontations with Iraqi and U.S. forces unless the Americans try to move deep into Sadr City, which has been under siege for two weeks.
The officials said the Sadrist leadership was concerned that the ongoing clashes were turning into a war of attrition that was weakening the movement and undermining support within its Shiite power base.
The officials spoke on condition of anonymity because they were not supposed to discuss policy with outsiders.
In a move to bolster its image among Sadr City residents, the government Saturday lifted a ban on entering and leaving the district, home to some 2.5 million people. Police announced that one of the entrances had been opened to motor traffic.
Army patrols warned residents through loudspeakers to keep off the streets, saying the rebels had planted roadside bombs that needed to be cleared by the security forces.
Fighting also continued Saturday against Sunni insurgents in the north.
In Mosul, a suicide bomber rammed his vehicle Saturday into a U.S. Bradley Fighting Vehicle, detonating a nearby fuel truck. No American soldiers were killed or injured, but one Iraqi child died and four people were wounded, U.S. officials said.
U.S. and Iraqi troops killed five Sunni al-Qaida fighters and captured two in a joint air assault in Salahuddin province north of Baghdad, the U.S. military said.
Elsewhere, Iraqi soldiers acting on tips from detained Shiite militiamen found 14 bodies that had been buried in a field south of Baghdad, officials said Saturday. It was the second discovery this week of mass graves in the area, raising to 45 the number of bodies located there.
The victims are believed to have been killed more than a year ago as part of a cycle of retaliatory violence between Shiites and Sunnis that has since ebbed.
Recent clashes in the Baghdad area have severely strained a unilateral truce which al-Sadr imposed on the Mahdi Army last August. He ordered the standdown to allow time to reorganize the force and purge criminal factions that had tarnished the image of his movement.
U.S. officials have acknowledged that al-Sadr's truce, along with the Sunni Arab revolt against al-Qaida, had played a major role in reducing American and Iraqi deaths, especially in the Baghdad area.
With renewed Shiite militia fighting, Baghdad is now accounting for a growing number of American casualties.
Last month, 61 percent of the U.S. military deaths occurred in Baghdad, compared with 28 percent in February and 47 percent in April, 2007, according to figures compiled by The Associated Press.
Fighting in Baghdad broke out following last month's ill-prepared Iraqi government offensive against Shiite militias and criminal gangs in the southern city of Basra.
The offensive stalled in the face of fierce resistance by the militias, whose allies in the capital showered rockets and mortars on the U.S.-controlled Green Zone.
Although fighting has eased in Basra, U.S. and Iraqi troops have been pressing militias in Baghdad's Sadr City to drive them beyond rocket range to the Green Zone.
Associated Press reporter Sameer N. Yacoub in Baghdad and the AP's News Research Center in New York contributed to this report.