Kabul - An Afghan provincial governor said Monday that US- led coalition military forces killed 14 security guards working with a road construction company in eastern Afghanistan, while the US military claimed those killed were militants.

The incident happened close to Khost, the provincial capital of like-named south-eastern province, on late Sunday when coalition forces opened fire on three vehicles, Khost governor, Arsala Jamal said.

He said all those killed were Afghan security guards, who were working for a road construction company in the province.

The US military said in a statement on Monday that their forces stopped three vehicles close to Khost city, but the "occupants of the vehicles got out of their vehicles and fired on the Coalition forces."

The statement said the coalition soldiers returned fire with rifles and helicopter gun fire, adding, "there were secondary explosions in the vehicles, and 14 armed men were killed."

Numerous ammunition belts and small arms were recovered from the vehicles, the statement said, adding that a joint investigation with Afghan government officials was underway to clarify the facts surrounding the incident.

President Hamid Karzai condemned the incident and warned that these kinds of incidents in which civilians die would erode public support for the Afghan government and for the presence of international forces in the country.

There has been a series of incidents in which the US-led coalition and NATO-led forces have mistakenly or based on false information attacked Afghan security forces.

In a similar incident last month the US military said they had killed multiple insurgents during an operation in southern Ghazni province. But Afghan provincial officials said later that 23 security guards working with a construction company were killed in a coalition airstrike.

Also last month, US-led forces killed nine Afghan national army soldiers in an incident, also in Khost province.

Mounting civilian and Afghan security forces' casualties in international military attacks have angered Afghan government officials and the public.

President Karzai lashed out at US military forces for the deaths of 37 civilians, who were killed in a US-led anti-insurgency operation in Shah Wali Kot district of southern Kandahar province on Monday last week.

Following a joint investigation with the Afghan government, the US military acknowledged the 37 civilian deaths including women and children as well as the wounding of up to 30 others. (dpa)