A Nato official in Kabul said on Thursday that 20 fighters were killed in Wednesday's raid in Zari district, but had no further details. District police chief Ghulam Rasool said 22 died.

Residents said at least one woman was also killed in the raid  They said cluster bombs were dropped in the attack on the district, scene of a major Nato offensive in September in which hundreds of Taliban were killed.

The Taliban said only two fighters were killed in the strike, which they said came after an ambush of Nato vehicles.

Civilian toll

More than 3,100 people, about a third of them civilians, have been killed in operations by foreign forces this year against Taliban fighters.

Rasool said six more Taliban were killed in an encounter with police close to Zari on Thursday, while several Taliban and police died during a clash on Wednesday in Zabul province, adjacent to Kandahar.

Kandahar is the birthplace of the Taliban, whose government US-led troops overthrew in 2001.

Nato assumed full security responsibility of Afghanistan from the US-led coalition in September, the biggest military operation in the alliance's history.