An Afghan soldier turned his weapon on NATO allies Thursday in the latest in a series of so-called green-on-blue attacks, the US-led International Security Assistance Force said.

"We can confirm that an ANA soldier fired on ISAF members in Laghman province. They returned fire, killing the attacker," an ISAF spokesman told AFP.

No ISAF soldiers were killed in the attack in the eastern province, he said, but in line with policy would not confirm whether any had been wounded.

The shooting is the latest in an increasing number of incidents in which Afghan soldiers have turned their weapons against NATO troops helping Kabul fight a decade-long insurgency by Taliban Islamists.

Just two days ago, an American solider was killed in the east when two men in Afghan army uniforms opened fire on their allies.

A US defence official said the two suspected shooters were in custody and an investigation was under way to determine whether they were Taliban infiltrators.

The death took the green-on-blue toll this year to around 30, in some 22 such incidents, according to an AFP tally.

Some of the attacks are claimed by the Taliban, who say they have infiltrated Afghan army ranks, but many are attributed to cultural differences and antagonism between local and US-led allied forces.

Some 130,000 NATO troops in Afghanistan are preparing to withdraw in 2014 and are training and working alongside Afghan soldiers as they take increasing responsibility for the anti-insurgency campaign.