NATO troops opened fire on a police patrol in southern Afghanistan, apparently mistaking them for hostile forces, and killed five policemen, a senior police official said on Friday.
Another six policemen were missing after the shooting late on Thursday in the volatile Gereshk area of the southern province of Helmand, provincial deputy police chief General Isau Khan said.
They had been travelling in a vehicle that was not a conventional police type, he said.
The media office of NATO's International Security Assistance Force could not confirm the incident.
However, a military official in southern Afghanistan said on condition of anonymity that there had been an incident between NATO forces and the police overnight which was believed to have caused police casualties.
The circumstances of the incident were unclear, the official added.