An Afghan in a security forces uniform turned his gun to foreign special forces personnel on Saturday killing three soldiers and wounding another, Afghan and Western military officials said.
"Three International Security Assistance Force service members died when an individual wearing an Afghan National Security Forces uniform shot them in eastern Afghanistan today," ISAF said in a statement.
An Afghan official, speaking on condition of anonymity, said the three soldiers killed were special forces, though he declined to comment on their nationality.
"We can confirm that three ISAF service members were killed and one wounded by an individual wearing an ANSF uniform in Gardez," said Afghan Defense Ministry spokesman General Zahir Azimi.
The attacker was shot dead by Afghan soldiers immediately after the attack, Azimi said.
US forces provide the bulk of ISAF troops in the east of Afghanistan. The attack was the seventh reported insider attack this year, and 12 ISAF personnel have been killed.
The last reported insider attack was on July 9, when an Afghan soldier at a military base in Kandahar shot dead one soldier and wounded three others.
Last year saw a record number of such attacks. Figures have dropped considerably this year, partly due to increased security and partly due to a reduction in the interaction between Afghan soldiers and their foreign counterparts, Western officials have said.
RA/HH