Afghan officials have confirmed the deaths, with interior ministry spokesman Nasrat Rahimi saying nine police were killed and 14 wounded in the aerial bombardment in Azra district of Logar province.

During the hours-long battle with insurgents overnight, police "called in air support but unfortunately foreign forces mistakenly bombed their positions", Rahimi said.

The Taliban also suffered heavy losses, he added.

Provincial council chief Hamidullah Hamid told AFP "foreign forces" had mistakenly bombed two police checkpoints and killed "about 15 police".

Resolute Support, NATO's mission in Afghanistan, confirmed US forces had conducted an air strike "in defense of Afghan forces" in Azra district but did not mention casualties.

"We are looking into the matter further," spokesman Lieutenant Colonel Martin O'Donnell told AFP.

The US is the only international force known to be carrying out air strikes in Afghanistan. The Afghan air force also carries out some attacks.

There are about 14,000 US ground troops in Afghanistan, making up the bulk of NATO's mission to support and train local forces.

Some of the US forces are involved in counter-terrorism operations, particularly against the Islamic State jihadist group.