Afghan and international troops have killed more than 100 Taliban militants in several clashes in the troubled southern province of Helmand over the past three days, the US-led coalition said Thursday.

Helmand is a stronghold of the extremist Taliban movement that was in government between 1996 and 2001 and is waging an insurgency to take back power.

"Afghan National Security Forces and coalition forces killed over 100 insurgents during combat operations in Helmand province August 25-28," the coalition said in a statement.

"Numerous engagements" were sparked when troops were attacked several times by insurgents armed with guns, rocket-propelled grenades and mortars, it said.

"The patrols returned fire and called in close-air support against the insurgents," it added.

It was not possible to independently verify the figures, announced two days after a United Nations team said it had found "convincing evidence" that 90 civilians, 60 of them children, were killed in US-led air strikes last week.

The US-led coalition had said only that 30 Taliban died in the strikes, but acknowledged on Tuesday that five civilians -- two women and three children -- were killed along with 25 Taliban.

Southern Afghanistan has seen some of the worst of the insurgency, with several areas said to be in Taliban control including in Helmand province which has recently seen weeks of clashes with officials regularly saying high numbers of fighters have been killed.

The coalition's use of air power has come in for renewed criticism after the UN and Afghan investigations said the 90 civilians, including 60 children, were killed in strikes in the western province of Herat a week ago.

The coalition announced earlier Thursday that one of its soldiers was killed while on patrol in southern Afghanistan.

It gave no details about what had happened, or the nationality of the soldier, saying only the incident was "under investigation". It was unclear if the soldier died in the Helmand clashes.