Kabul: A US air strike killed five Afghan policemen during a joint operation against insurgents, officials said on Thursday, in an incident likely to further strain ties between the allies.
Afghan and US troops 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 a Taliban 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 a news agency.
"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."
Accidental 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 coalition due to withdraw its 100,000 combat troops by the end of 2014, the Afghan police and Army are increasingly taking responsibility for tackling the insurgency that erupted after the Taliban were ousted in 2001.
Ahmad Zia Abdulzai, spokesman for the Nangarhar provincial administration, told a news agency that Taliban fighters had attacked a police checkpoint in Bati Kot district late on Wednesday.
"Special forces went to assist the police. They called in air support. An air strike was conducted but hit the police post mistakenly, and as a result the officers are dead and two others are wounded."
Abdulzai said that the rebels also suffered casualties but he gave no further details.
Bati Kot district is on the main road from the capital Kabul to neighbouring Pakistan -- a key transport route as NATO forces withdraw military equipment from Afghanistan.
Talks on whether a number of American troops would remain in Afghanistan beyond 2014 -- to target remaining al Qaeda militants and further train Afghan forces -- collapsed in June when Karzai was angered by the opening of a Taliban office in Qatar.
The Taliban issue was just one in a series of spats between the nations, which also included which country should have control over prisons holding suspected insurgents.