A gunman has shot dead a member of the US-led international coalition in southern Afghanistan on Saturday before being killed, Nato has said in a statement.

The gunman may have been a private security member of staff, according to a coalition statement that blamed the shooting on an "alleged contracted security guard." It did not say if he was an Afghan or foreign national and gave no other specific details.

"The scene of the incident is secure and the suspected gunman has been killed," the statement said. It added that the coalition and "Afghan officials are assessing the incident and more information will be released as appropriate."

The coalition also said confirmed that one of its service members died of a non-battle related injury in the south. No other details on the incident were provided.

The perimeters of many coalition facilities, embassies and international organizations are guarded by Afghan guards contracted from a government agency that provides such services. Internal security at many facilities is provided by foreign guards contracted from multi-national security corporations.

Last year also saw a spate of "insider attacks" carried out by uniformed Afghans against foreign soldiers and civilians. In some cases, militants have donned Afghan army or police uniforms to attack foreign troops, but a number have been carried out by members of Afghan security forces against their own comrades.

The two deaths bring the death toll total among foreign forces to 128 so far in 2013, of which 98 are from the United States.

Earlier, an Afghan official said a NATO strike in the country's east had killed five civilians, but the US-led coalition said that it targeted insurgents and that its initial reports indicate no civilian casualties.

Provincial spokesman Ahmad Zia Abdulzai said the strike killed five civilians. He did not provide any more details about the circumstances.

LT. Col. Will Griffin, a spokesman for the coalition, said that the late Friday attack in Nangarhar province, near an airport used by NATO forces, was dealt with using a "precision coordinated strike."

Afghan and Nato officials regularly differ as to whether civilians have been hit in attacks. Afghan President Hamid Karzai has made denunciations of reported civilian deaths in airstrikes a pillar of his political strategy.

Insurgents have increased attacks in recent months as they intensify a campaign to regain territory as foreign forces drawdown ahead of a full withdrawal at the end of 2014.

Additional reporting by Associated Press