Cambodia's former president under the Khmer Rouge, Khieu Samphan, was charged on Friday with genocide by a U.N.-backed war crimes court.

The French-educated guerrilla leader, now 78, was arrested in 2007.

Samphan has portrayed himself as a virtual prisoner of the regime and denied knowledge of any atrocities.

Similar charges of genocide were issued on Wednesday against "Brother Number Two" Nuon Chea and former Foreign Minister Ieng Sary.

The two men were allegedly involved in the slaughter of Cambodia's ethnic Vietnamese and Cham Muslim minorities during the Khmer Rouge regime.

All three have already been charged with war crimes and crimes against humanity for their part in a bloody agrarian revolution from 1975 to 1979 under the leadership of Pol Pot, who died in 1998.

The charges come three weeks after the end of the first trial of a senior Khmer Rouge cadre.