The death toll of Nato troops being killed by Afghans in uniform has now reached 18 this year. -File Photo

KABUL: A man in an Afghan army uniform opened fire on Nato allies, killing one soldier before being shot dead, the Nato-led force in Afghanistan said Thursday.

“An individual wearing an Afghan National Army uniform turned his weapon against coalition service members in southern Afghanistan late yesterday, killing one service member,” Nato's International Security Assistance force (ISAF) said.

“The individual who opened fire was killed when coalition forces returned fire,” an ISAF statement said, adding that the nationality of the dead Nato soldier would be released in his home country.

The shooting is the latest in a series of similar incidents in which Afghan soldiers have turned their weapons against Nato troops helping the Afghan government fight an insurgency by hardline Taliban militants.

The death takes the toll of foreign troops killed by Afghans they were working with to 18 this year -- including seven Americans and five French trainers -- in 11 separate attacks.

ISAF, which is training Afghans to take over responsibility for security for the whole country by the end of 2014 when foreign troops pull out, has said the deaths sap spirits among its troops.

“Although the incidents are small in number we are aware of the gravity they have as an effect on morale,” ISAF spokesman Brigadier General Carsten Jacobson said in Kabul earlier this month.

“Every single incident has an out-of-proportion effect on morale and that goes for coalition forces as it goes for Afghan national security forces.”

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 the allied forces.