Such ceremonies—once banned by the Khmer Rouge—are allowed under the internal rules of the UN-backed court.
The announcement from the court moves it a step closer to the second phase of the trial against the two men, in the court’s most prominent trial to date.
Many younger Cambodians do not know what happened during the Khmer Rouge.
Both leaders on trial will face charges related to the treatment of the Chams, as well as Vietnamese, when their trial begins in full later this year.
Many Cambodians felt the court’s slow pace and limited scope were not bringing them a sense of justice.
The Documentation Center of Cambodia, a key research facility for the atrocity crimes of the Khmer Rouge, plans to start building a genocide institute that will be the first of its kind in Asia.
Nuon Chea is on trial alongside Khieu Samphan, another regime leader, for atrocity crimes.
Nearly half a million Cambodians fled the regime to live in the United States, leaving behind family members who were killed.
Scot Marciel, the top diplomat for Asia and Pacific at the US State Department, said the tribunal can serve as an example to Cambodians and the world.
Observers say they are hopeful the case will reveal more truths about the movement and provide some sense of justice for victims.
A researcher says interviews with many everyday Cambodians shows a desire to hear confessions from two former leaders.