The NATO-led force in Afghanistan has launched an investigation into the accidental killing of five Afghan policemen in a US air attack during an overnight operation.

Two policemen were also wounded in the incident Wednesday night, Reuters reported.



Afghan special forces called in for air support during a confrontation with a group of Taliban fighters at a police checkpoint, said Ahmad Zia Abdulzai, a spokesman for the governor of the eastern province of Nangarhar.



NATO confirmed the strike. "A US aircraft engaged, inadvertently killing five Afghan National Police members," said Master Sergeant Bryan Gatewood, a spokesman for the NATO-led force. "An investigation is ongoing to determine additional details of this unfortunate incident," he continued.



Western forces causing accidental casualties are a major source of contention between President Hamid Karzai and the governments involved and Karzai had previously ordered a ban on his troops calling them in.



The latest incident comes just as the US is attempting to kick start talks with Karzai's government on the size of the military presence after international troops are withdrawn next year.



The mountainous region which lies on Afghanistan’s border with Pakistan has long been infamous as an insurgent hotspot. Foreign air power is deemed necessary to cover the area as Afghan security forces have insufficient air power.



