Nuon Chea, left, who was the Khmer Rouge's chief ideologist and No. 2 leader, waits before his final statements at the U.N.-backed war crimes tribunal in Phnom Penh, Cambodia, last year. Pic: AP.

PHNOM PENH, Cambodia (AP) — A U.N.-backed tribunal is holding a hearing to prepare for the genocide trial of two surviving leaders of Cambodia’s Khmer Rouge, under whose rule an estimated 1.7 million people died in the late 1970s.

Khieu Samphan, the regime’s head of state, and Nuon Chea, another senior leader, are already set to face sentencing next week after being tried for crimes against humanity involving mostly the group’s forced movement of millions when it took power in 1975.

Their second trial, supposed to begin by the end of this year will also cover crimes against humanity and add charges of genocide for the killings of members of Cambodia’s Vietnamese and Cham ethnic minorities.

This week’s initial hearing will consider technical matters such as witness lists and procedural objections by the contending parties.