A bomb dating back to NATO's 1999 campaign in Serbia killed two military deminers when it exploded on Wednesday, the defence ministry said. The pair, both members of the air force, were killed in a blast on Kopaonik mountain in southern Serbia, a ministry statement said. Local media reported that the men died in explosion from a cluster bomb dropped during the bombing campaign aimed at ending Serbia's crackdown on Kosovo's restive ethnic Albanian population. The 77-day bombing ended the Kosovo 1988-1989 conflict.