Six Afghan national security force members were killed while fighting Taliban militants in southwestern Farah province, an army official said on Saturday.
Three other members of the Afghan National Security Forces were injured and 11 Taliban militants killed in the operation in Bala Buluk district late Friday, said a spokesman for the Afghan army.
Local media said that the six had died as a result of an airstrike by foreign forces, but the Afghan army and NATO dismissed those reports.
"Allegations of a US airstrike in Farah province are false," NATO's Resolute Support mission said on Twitter, adding that the US has not conducted any airstrikes in the province in the past week.
Eight highway police officers were killed in a US airstrike in southern Uruzgan province in late September.
The UN Assistance Mission in Afghanistan on Thursday condemned the killing of 15 civilians and wounding of another 13 by a US airstrike targeting Islamic State militants in eastern Nangarhar province.