Afghan policewoman kills American advisor

KABUL -- An Afghan police officer has killed a U.S. adviser at a police station in Kabul, news agencies quoted the Afghan police representatives as saying.

An investigation is ongoing and is expected to determine "whether the killing occurred intentionally or accidentally", western news agencies reported.

Head of the investigation department of the police, Mohammed Zahir, described the incident as an "insider attack" - an attack in which Afghan security forces turn their weapons against the Western coalition forces, with which they are supposed to work together.

This is the first time a woman, a member of the Afghan security forces, has killed a member of the Western coalition troops in such an insider attack.

Afghan soldiers and police have killed at least 53 coalition troops this year.

NATO forces have accelerated efforts to train Afghan security forces before the planned withdrawal from that country in late 2014.

In a separate incident of a similar nature in northern parts of the country, an Afghan policeman on Monday "killed five colleagues, and escaped to join the Taleban", according to local authorities.