KABUL: A man wearing Afghan security forces uniform shot dead three Nato-led soldiers on Saturday in the eastern part of the war-torn country, the coalition said.

So-called “insider attacks”, in which Afghan forces turn their guns on their foreign partners, have killed scores of foreign troops in Afghanistan, breeding fierce mistrust and threatening to derail the training of local forces to take over security duties ahead of Nato’s withdrawal next year.

“Three International Security Assistance Force (ISAF) service members died when an individual wearing an Afghan National Security Forces uniform shot them in eastern Afghanistan today,” an ISAF statement said, adding that both ISAF and Afghan officials were investigating the incident.

In line with Nato policy, the statement did not give the victims’ nationalities.

An Afghan official, speaking on condition of anonymity, told AFP that the incident happened during a training session in the insurgency-hit eastern province of Paktia.

An Afghan National Army (ANA) soldier opened fire on US soldiers in a military training camp, killing two on the spot, he said. A third later died of his wounds, he added.

The attacker was killed when Americans returned fire, he said.

The threat of “insider attacks” has become so serious that foreign soldiers working with Afghan forces are regularly watched over by so-called “guardian angel” troops to provide protection from their supposed allies.

There are presently some 87,000-strong US-led forces fighting alongside about 350,000 Afghan security forces to repel a bloody Taliban insurgency which has been going since 2001.