KABUL (AFP) - A bomb killed at least six local security guards in eastern Afghanistan on Wednesday, officials said, in the latest attack linked to a mounting insurgency in the war-torn country. The US military said the six men killed in the bomb blast in the eastern province of Khost were with police and on a routine patrol. Another three were evacuated for medical treatment by the US-led coalition, media officer Chief Brian Naranjo told AFP. Afghan sources said on condition of anonymity, however, that seven men were killed in the bombing, which blew up a vehicle, and that the men were with a private security group employed by foreign forces. Attacks reached a record high last year and Washington is rethinking its efforts to help defeat the violence and stabilise Afghanistan, which was left in tatters by decades of war that started with the 1979 Soviet invasion.