Villagers in southern Afghanistan say that dozens of civilians, including women and children attending a wedding party in Kandahar, have been killed in a US air raid.
Hamid Karzai, the Afghan president, condemned the killings and said on Wednesday that 40 people were killed and 28 wounded as a result of an air raid in the Shah Wali Kot district of Kandahar province.
US officials in Afghanistan confirmed that a number of civilians had been killed and said that an investigation was under way.
"We acknowledge some civilians have been injured and some may have been killed," Colonel Greg Julian, a spokesman for the US forces in Afghanistan, told the AFP news agency.
"I can't confirm numbers," Julian said, adding the military regretted every time civilians became "collateral damage" when troops tried to take out anti-government fighters.
Witnesses accompanying the wounded to Kandahar's main hospital said the dead included at least 23 children and 10 women.
"Seven women, including the bride, and three children were admitted to hospital in Kandahar," an AFP news agency reporter said.
Local residents said the attack was carried out after Taliban fighters fired on a US convoy in the Shah Wali Kot area of the province on Monday.
David Chater, reporting for Al Jazeera from Afghanistan, said he had been told by a cameraman that a coalition patrol had gone through a village and was fired on by Taliban fighters.
"As a result of that Taliban fire they called in closed air support and there was a wedding party going on in that village - there were some 90 people in a house - and the missile landed there," he said.
Roozben Khan, the father of the bride, said he had lost six relatives.
"I lost two sons, two grandsons, a nephew, my mother and a cousin," Khan said.
His daughter was among seven of his relatives who were wounded. The groom survived but his father, mother and sister were killed, he said.
Mullah Mohammad Asim, the village cleric, said he had counted 36 bodies.
"They bombed six to seven houses. They pounded and fired into the village from afternoon until midnight," Asim said.
"At midnight, the Americans came and they took the men out of the houses and handcuffed them. But when they saw the death and the destruction, they removed the handcuffs and told us to take the wounded to hospital," he said.
The bombing is the latest in a string of incidents in which the US military has been accused of attacking innocent civilians.
The attacks have caused major friction between the US and the Afghan government.