KABUL (AFP) - Two Afghan men wearing military uniforms shot dead two NATO soldiers on Wednesday, in the first suspected "insider attack" of the year as international troops withdraw after 13 years of fighting Taleban militants.

Incidents in which Afghan forces turn their guns on their allies have killed scores of US-led troops, breeding fierce mistrust and undermining efforts to train up local forces to secure the country.

"Two International Security Assistance Force (ISAF) service members died when two individuals wearing Afghan National Security Forces' uniforms shot them in eastern Afghanistan," the NATO force said in a statement.

"ISAF and Afghan officials are assessing the incident to determine the facts." The incident happened in the province of Kapisa, north of Kabul, provincial governor Mehrabudin Safi told AFP, giving no further details.

Taleban spokesman Zabiullah Mujahid claimed the Islamist militants were responsible for the killings.

But ISAF officials say that most insider attacks stem from personal grudges and cultural misunderstandings rather than Taleban insurgent plots.

The number of such attacks fell sharply in 2013, but the threat still means that foreign soldiers working with Afghan forces are regularly watched over by so-called "guardian angel" troops to provide protection.

Afghan soldiers and police are taking on responsibility for battling the Taleban from about 55,000 NATO combat troops who will leave by the end of 2014 - 13 years after a US-led invasion brought down the Taleban regime.

In line with coalition policy, the NATO statement said casualty identification would be left to the victims' national authorities.