Nato confirmed that an air strike was called in by a convoy involved in a firefight in Ghazni province in eastern Afghanistan. - AFP File Photo

KABUL: Nato troops clashed Tuesday with private security guards who were apparently escorting a supply convoy for international troops, sparking a firefight in which the alliance called an air strike that killed at least five of the guards, Afghan police said.

Nato confirmed that an air strike was called in by a convoy involved in a firefight in Ghazni province in eastern Afghanistan, but it said initial reports suggested the strike was on insurgents.

The international coalition said it could not yet confirm anything more about the incident in the province's Gelan district.

''The convoy called for and received close air support. We are still assessing the results from the engagement,'' a Nato statement said.

Afghan officials said there were no insurgents involved in the conflict, which started sometime after dawn.

''This morning, there was some sort of incident between an American convoy and security guards from Watan Risk,'' said Zirawer Zahid, the police chief of Ghazni. He was referring to Watan Risk Management, a private company that supplies guards for convoys, offices and international organisations.

Zahid did not have details on what sparked the fighting, but he said that the NATO air strike that followed killed at least five of the Watan guards. Watan could not immediately be reached for comment.

It was not immediately clear if the Nato troops and the guards were part of the same convoy or if there were two separate convoys that got involved in the fighting.

Also Tuesday, a Nato service member was killed in a pre-dawn bomb attack in the east. There were no further details on the attack or the nationality of the deceased.

More than 150 international service members have been killed so far this year in Afghanistan.

The war in Afghanistan has continued uninterrupted following the deadly strike against al Qaeda leader Osama bin Laden in neighboring Pakistan. Both US officials and their Afghan counterparts have said that there is still a powerful terror network to fight in Afghanistan even after the death of bin Laden and that their military strategy remains unchanged. – AP