A homicide car bomber struck a U.S. military convoy passing through a crowded market in eastern Afghanistan on Thursday, killing at least eight civilians and a U.S. soldier and wounding an additional 74 civilians, Afghan officials said.

Separately, two British troops were killed Wednesday in an explosion in southern Afghanistan, Britain's defense ministry said in a statement. Their vehicle was struck by an explosive while they were on a patrol with Afghan security forces.

The homicide attack that hit the American patrol in the east occurred in Bati Kot district of Nangarhar province, said Lt. Cmdr. Walter Matthews, a U.S. military spokesman.

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No one took responsibility for the bombing, but Taliban militants regularly use homicide attackers and car bombs in their assaults against Afghan, U.S. and other foreign troops in the country, although civilians are the most frequent victims of such attacks.

At least eight civilians were killed and 74 others were wounded in the attack, said Ghafoor Khan, spokesman for the provincial police chief. An American soldier was also killed in the bombing, the U.S. military said.

The number of civilians killed in the attack reported by Khan is significantly lower than an earlier report by the U.S. military, which said 20 civilians had died. Later, the military declined to put a number on the dead civilians and referred calls to Afghan authorities.

The bomber struck the convoy near a crowded livestock market where people were trading sheep, cows, goats and other animals, Khan said.

Hours after the attack, charred and twisted remains of cars smoldered on the tree-lined street that is also Afghanistan's main road to the Pakistan border at Torkham.

An Associated Press photographer said an American military vehicle, two civilian vehicles and two rickshaws were destroyed.

The wounded civilians were transported to at least three hospitals in the provincial capital of Jalalabad, Khan said.

The United Nations condemned the bombing, which it said "inflicted enormous suffering in an otherwise peaceful community."

More than 5,400 people, including nearly 1,000 civilians, have died in insurgency-related violence this year in Afghanistan, according to a tally by The Associated Press of figures provided by Afghan and international officials.

The U.S. soldier's death brings the number of U.S. troops killed in Afghanistan this year to at least 148, the highest annual number of troop deaths since the U.S.-led invasion in 2001. There were 111 U.S. military deaths in Afghanistan in all of 2007.

The attack in Nangarhar follows a truck bomb blast Wednesday in southern Afghanistan which killed six people and wounded 42.

The blast in Kandahar city, the Taliban's former stronghold, came as the provincial council was hearing constituent complaints. Two members of the council were wounded in the attack, said Kandahar Gov. Rahmatullah Raufi.