Afghan President Hamid Karzai has accused the United States of killing seven children and one woman in an airstrike, an incident set to further damage frayed ties between the two allies.

The presidential palace in a statement released on Wednesday condemned last night's airstrike in Seagard District of Parwan province.

"As a result of bombardment by American forces last night, which was conducted...one woman and seven children were martyred and one civilian injured," the statement said.

"The Afghan government has been asking for a complete end to operations in Afghan villages for years, but American forces acting against all mutual agreements and guarantees have once again bombarded a residential area and killed civilians."

Sensitive issue

Civilian casualties have been one of the most sensitive issues of the 13-year military intervention in Afghanistan, and Karzai has often used accidental shootings and misguided airstrikes to berate American-led international troops.

NATO's International Security Assistance Force (ISAF), earlier said it was "aware of reports that at least two civilians were inadvertently killed on Wednesday during an Afghan-led joint operation in Ghorband (Siahgird) District".

"An enemy force engaged Afghan and coalition forces from several compounds," it said. "Afghan and coalition forces returned fire and required defensive air support to suppress the enemy fire."

ISAF added that one of its soldiers was killed in the fighting, as well as at least 10 fighters.

Seagard district, about 40km north of Kabul, is on the main road from the capital to Bamiyan. The route was considered safe, but the region has become increasingly violent.