International Security Assistance Forces honor guards take part in a flag-lowering ceremony in Kabul, Afghanistan on December 8, 2014. (Associated Press photo)

Afghanistan's NATO-led foreign force mistakenly killed three civilians in an air strike, Afghan officials said today, less than a week before most foreign troops are due to pull out at the end of a 13-year mission.The mistaken killing of civilians in air strikes has been a source of anger throughout the force's mission, frequently straining ties between the NATO force and the government.The latest incident took place in Logar province just south of the capital, Kabul, on Friday, and it involved nomads who had clashed in a dispute over land, provincial officials said.Authorities in the area were negotiating a ceasefire but NATO's International Security Assistance Force (ISAF) apparently mistook the nomads for insurgents preparing an attack, officials said."ISAF launched an air strike which killed three people and wounded two," said Logar police chief Abdul Hakim Ishaqzai.He said it was common for nomads, who move around the country with flocks of livestock, to be well-armed. Disputes over grazing land are common."The people who were killed were inside a house," he said.

© Thomson Reuters 2014

The NATO force did not immediately respond to a request for comment but said it would issue a statement later.At least 3,188 civilians have been killed Afghanistan in 2014, according to the United Nations, a nearly 20 per cent rise on the previous year and the highest since the United Nations began keeping records in 2009.