KABUL: An Afghan policewoman killed an American adviser at the Kabul police headquarters, an Afghan police official said.

Kabul's Deputy Police Chief Mohammad Daoud Amin said an investigation was underway to determine whether the killing Monday was intentional or accidental.

It was not known whether the victim was a military or civilian adviser.

The Nato military command said it was looking into reports of the shooting but had no independent information.

At least 53 international troops have been killed by Afghan soldiers or police this year, and a number of other assaults are still under investigations.

Nato forces, due to mostly withdraw from the country by 2014, have speeded up efforts to train and advise Afghan military and police units before the pullout.