Two US soldiers and an American civilian have been killed in a insider attack in eastern Afghanistan.
''An individual wearing ANA (Afghan National Army) uniform turned his weapon against ISAF service members," a statement said. He was shot dead.
The incident took place on Saturday in Paktika province, close to the border with Pakistan.
A BBC correspondent in Kabul said there was a spate of insider attacks on foreign troops last year but the last was more than a month ago.
Last September, NATO announced it was limiting joint patrols with Afghan forces and only large operations would be conducted jointly.
About 7000 new recruits per month join the Afghan army alone. Correspondents say it is a huge challenge to ensure Taliban fighters do not slip through the net.
