Five security guards escorting a Nato coalition supply convoy and more than a dozen insurgents have been killed in a three-hour fight in western Afghanistan, Afghan officials say. Najibullah Najibi, who is a spokesman for the Afghan National Army's western region, said insurgents attacked the coalition convoy in the Bala Buluk district of Farah province. Sayed Abdul Wahid, who is an official of the Arya security company, said his workers who were fighting with AK-47s were overpowered by militants using heavy weapons, including rocket-propelled grenades. He said five of his employees were killed and five others were wounded by insurgents who burned three vehicles in the convoy. Mr Najibi said at least 14 insurgents were killed.