Men wearing Afghan military uniforms shot dead two NATO soldiers in the country’s south Wednesday, the coalition said.

Men wearing Afghan military uniforms shot dead two NATO soldiers in the country's south Wednesday, the coalition said.

So-called "green-on-blue" attacks -- when Afghan soldiers or police turn their guns on international troops -- have been a major problem during NATO's long years fighting alongside Afghan forces.

No group has so far claimed responsibility for Wednesday's attack in the volatile province of Helmand.

"Two Resolute Support (NATO) service members died early this morning when two individuals wearing Afghan (military) uniforms opened fire on their vehicle at an (Afghan security forces) compound in Helmand province," a NATO statement said.

"Resolute Support service members returned fire and killed the shooters," it added, without revealing the nationalities of the foreign soldiers.

The statement did not give the precise location of the attack, which highlights long-simmering tensions between Afghan and foreign forces.

It was the first such incident since Mullah Akhtar Mansour was named the new Taliban chief following the announcement of the death of longtime leader Mullah Omar.