Twelve Afghan security forces personnel were killed after an aircraft mistakenly pounded their positions in Helmand province, reports said Monday.

“The airstrike took place in Otrang village of Gereshk district on a position where Afghan troops were involved in operations against the Taliban,” an Afghan defence official was quoted as saying by  Xinhua news agency.

Helmand governor Hayatullah Hayat told news agency AFP that the area has been the scene of heavy fighting over the past several days.”

Both the Afghan and American militaries use air power. Hayat’s spokesman Omar Zwak told the New York Times, “We are investigating which air force had carried out the strike.”

Defense Ministry officials have told the local news media that Afghan aircraft were responsible, the Times reported.

Maj. Kendra Motz, a spokeswoman for the American Marine advisory mission in Helmand Province, said the strike had not been carried out by American forces.

The incident comes more than two months after a US airstrike killed 16 Afghan police and wounded two others in the same district, large parts of which are under Taliban control.

A US airstrike in the Afghan capital Kabul a few days ago wounded six members of the same family after a missile malfunctioned and landed on the wrong house, adding to the civilian toll from the grinding conflict.

“Airstrikes carried out by international and Afghan air forces caused 590 civilian casualties (in 2016), nearly double that recorded in 2015,” a separate UN report shows, with women and children accounting for more than half of the victims.

(Representative image)