JALALABAD: An Afghan commando Saturday killed two American soldiers and wounded two others during a joint operation in eastern Nangarhar province, a stronghold of Islamic State militants, an official said.

The Taliban claimed responsibility for the insider attack in the volatile district of Achin, saying it was carried out by an infiltrator.

"Today around noon an Afghan commando opened fire on US troops in Achin district, killing two American soldiers," provincial spokesman Attaullah Khogyani told AFP.

"The (Afghan) soldier was also killed in the return fire."

NATO forces in Kabul declined to immediately comment on the killings.

"We are aware of an incident in eastern Afghanistan," the US-led military coalition said in a brief statement. "We will release more information when appropriate."

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.

Western officials say most such attacks stem from personal grudges and cultural misunderstandings rather than insurgent plots.

The killings have bred fierce mistrust between local and foreign forces even as the rate of such incidents has dropped in recent years.

NATO troops have adopted special security measures in recent years to try to counter the threat.

Insider attacks have also plagued Afghan troops, depleting morale and causing mistrust within security ranks.