Three US soldiers have been killed by a gunman wearing Afghan army uniform in Helmand province, Nato has said.
Afghan officials told Reuters news agency that the three people killed were special forces members.
The official said they were shot while attending a meeting in the Sangin district late on Thursday.
It is the latest in a series of so-called "green-on-blue" attacks, where men wearing Afghan army uniforms turn their guns on coalition troops.
On Tuesday a US Nato soldier was killed by two gunmen wearing Afghan army uniform in eastern Afghanistan.