Violence has increased sharply across Afghanistan since foreign forces formally ended their combat mission last year, leaving a small contingent of about 12,000 NATO troops to train Afghan forces against a Taliban insurgency.
The foreign forces heading the Resolute Support mission said the incident took place in the restive province of Helmand, where government forces are frequently targeted by militant attacks.
“Two Resolute Support service members died early this morning, when two individuals wearing Afghan National Defense and Security Forces uniforms opened fire on their vehicle,” the alliance said in a statement.
The statement did not give further information on the exact location of the incident and nationalities of those killed, but most foreign forces operating in Helmand are American.
A regional official said the incident involved two apparent Afghan special forces firing on their allies at the former Camp Bastion, a major base handed over to Afghan forces last year.