PHNOM PENH -- Cambodia's UN-backed tribunal has charged Khieu Samphan, formerly head of the state for the Khmer Rouge regime, with genocide.
The 78-year-old former leader was charged over the massacres of Cambodia's Vietnamese and Muslim minorities during the Khmer Rouge 1975-79 rule.
He is the third Khmer Rouge leader to be charged with genocide this week, after the group's top ideologist, Nuon Chea, and the former foreign minister, Ieng Sary.
All three men had already been charged with war crimes and crimes against humanity.
Their trial is not expected to begin before 2011.
Up to 2 million people are thought to have died under the Khmer Rouge rule.
compiled from agency and BBC reports