KABUL, Sept 30: Two Americans were killed in Afghanistan during an exchange of fire between Nato-led forces and the Afghan army that could have been the result of a misunderstanding, as the death toll of US military and civilian personnel passed 2,000.

A US official said on Sunday that an American soldier and a civilian contractor had been killed in the incident in eastern Afghanistan, the circumstances of which remained unclear.

The coalition initially said the incident might have been the result of an “insider attack” and another example of a member of the Afghan national security force turning on coalition troops in a war that began in 2001. But it later said that nearby militant gunfire could have led to a misunderstanding.

“The circumstances were somewhat confused ... There was a report of insurgent firing taking place in this incident which we believe may have been a factor,” Lt-Gen Adrian Bradshaw, deputy commander of the Nato-led coalition, said.

It was the latest setback for the coalition after the United States said joint operations with Afghan forces were returning to normal.

Joint operations were halted two weeks ago after a surge of attacks on the Nato-led International Security Assistance Force (Isaf) by its Afghan allies. At least 52 Isaf service members have been killed this year in so-called “green-on-blue” attacks.

The suspension of joint operations was a blow for Nato which wants to train the 350,000 members of the Afghan security forces so that they may try to ensure stability after coalition forces withdraw.

Pentagon data listing the number of US troops and US contractors killed in Afghanistan since combat began 11 years ago showed the two new deaths pushed the total combined number of US personnel killed past the 2,000 mark.

The attack took place in the Sayed Abad district of the Wardak province, according to local police sources, who said a gunbattle had broken out between coalition soldiers and Afghans when an Afghan National Army member opened fire on American troops.

Three members of the Afghan National Army were also killed  in the firefight, while three other US citizens and one Afghan were wounded, police spokesman Wali Mohammad said on Sunday.

“We appreciate the sacrifice of our fallen heroes, every death is tragic and important — none more than any other,” Isaf said.—Reuters