Afghan president Hamid Karzai said yesterday an air strike by coalition forces earlier this week killed some 40 civilians and wounded about 28 in Kandahar province.
Mr Karzai called on US president-elect Barack Obama to make it his priority to stop the killing of civilians.
Scores of Afghans have been killed in US air strikes this year, leading to resentment against the presence of foreign troops and a rift between Mr Karzai and his Western backers.
The air strike took place on Monday in the Shah Wali Kot district in the southern Taliban heartland of Kandahar province.
Several villagers who had taken a group of wounded to the hospital in Kandahar city said the strike hit a wedding party. The US military said it was checking reports.
The incident happened during a clash between foreign troops and Taliban insurgents in Shah Wali Kot district.