A US air strike killed five Afghan policemen during a joint operation against insurgents, officials said Thursday, in an incident likely to further strain ties between the allies.
Afghan and US forces called for aerial support while fighting in the eastern province of Nangarhar, the US-led NATO coalition said, with local officials reporting special forces were reacting to an insurgent attack on a police post.
"We can confirm five Afghan police were accidently killed yesterday (Wednesday)," Lieutenant Colonel Will Griffin, a spokesman for NATO's International Security Assistance Force (ISAF), told AFP.
"It was a combined ANSF (Afghan National Security Force) and ISAF operation and it was a combined call for supporting aerial fire which resulted in the deaths of five Afghan policemen.
"Our condolences go out to the families of the policemen who lost their lives."
Civilian casualties from US air strikes have often provoked a furious reaction from Afghan President Hamid Karzai and the deaths of the five policemen come at a sensitive time for Afghan-US relations.
With the US-led NATO force due to withdraw its 100,000 combat troops by the end of next year, the Afghan police and army are increasingly taking responsibility for thwarting the insurgency that erupted after the Taliban were ousted in 2001.