Nato airstrike kills five Afghan policemen in overnight 'friendly fire' incident

The aircraft, believed to be a US helicopter, also injured two other special forces servicemen and destroyed part of a police checkpoint

Afghan security officials investigate a police checkpoint damaged in a NATO airstrike which accidentally killed five special forces officers (AP)

A Nato airstrike in Afghanistan has mistakenly killed five state policemen and wounded two others.

Afghan special forces were engaged in a clash with Taliban fighters at a police checkpoint on Wednesday night when they radioed for air support.

A US helicopter was scrambled to the scene in the eastern province of Nangarhar, where it proceeded to open fire.

“A U.S. aircraft engaged, inadvertently killing five Afghan National Police members and wounding two,” said Master Sergeant Bryan Gatewood, a spokesman for the Nato-led forces.

Afghan official spokesman Ahmad Zia Abdulzai confirmed the accident, blaming it on a “Nato helicopter”.

Sgt. Gatewood said: “An investigation is ongoing to determine additional details of this unfortunate incident.”

The deaths come as the US is attempting to restart talks with President Hamid Karzai’s government on the size of a foreign military presence after most international troops are scheduled to leave next year.

Unintended casualties caused by Western air strikes are a major source of friction between President Karzai and his international allies, and in the past he has ordered a ban on troops calling them in.

Yet air power is considered critical to the battle for control of the mountainous regions near the Pakistani border.

The region is a hot spot for insurgent strikes, and Nato argues it would only get worse for Afghans on the ground without the advantage of air support.

The Afghan national forces do not possess a significant air force of their own.