The deaths come amid a flare-up in violence across war-torn Afghanistan, where civilians are dying each day even as the US and the Taliban have claimed progress in an ongoing series of peace talks.

Six people were wounded in Sunday night's strike in the Baraki Barak district of Logar, some 70 kilometres (45 miles) southeast of Kabul, according to district governor Ahmad Wais Abdul Rahimzai.

"The air strike has hit two residential houses in the district," he told AFP, noting that the homes were occupied by Kuchi, an ordinarily nomadic people who sometimes settle in permanent structures.

"Two children are among those killed, and two women are among the wounded," he said.

Didar Lawang, a spokesman for the provincial governor, confirmed that the air strike had resulted in civilian casualties, but did not provide details.

It was not immediately clear who was behind the strike. US forces in Afghanistan declined to comment, but the Afghan defence ministry said it would issue a statement later.

The conflict in Afghanistan has in recent weeks intensified with both Afghan forces and the Taliban claiming to have inflicted heavy casualties on the other's forces.

The clashes have also killed or injured scores of civilians, including many children.

At least eight Afghan civilians were killed when a car bomb detonated near a major university in Kabul city last week.

Afghan officials blamed the Taliban for the bloodshed, though the militant group denied any involvement.