Donors, rights groups and the UN on Friday urged Cambodia's war crimes court to speed up the trial of the remaining two Khmer Rouge leaders accused of genocide after the death of an elderly suspect.
Regime co-founder Ieng Sary, 87, who was one of the few public faces of the Khmer Rouge, died in hospital on Thursday, escaping court judgment for his alleged role in the atrocities.
The two remaining defendants, Nuon Chea and former head of state Khieu Samphan -- who both deny charges of war crimes, genocide and crimes against humanity -- are in their eighties, prompting fears they too could die before the tribunal reaches a verdict.
The UN special rapporteur on human rights in Cambodia called on the court, its donors and the government to speed up proceedings at the much-delayed tribunal.
"We owe it to the surviving victims of the Khmer Rouge, the families of the victims, and the whole of Cambodian society that continues to suffer from the impact of the Khmer Rouge to this day," Surya Subedi said in a statement.
Only a handful of top regime figures have ever come to trial over the Khmer Rouge's crimes that saw a quarter of Cambodia's population wiped out in the late 70s.
The tribunal has been frequently cash-strapped since it was set up in 2006 to find justice for the deaths of up to two million people under the hardline communist Khmer Rouge regime.
It has been suspended since last week due to a strike by some local staff over unpaid wages, as a result of a row between donors and the Cambodian government.
In a joint statement the French and Japanese embassies in Cambodia, among the top donors, warned the trial must move ahead in a "fair, efficient and expeditious manner".
They also asked "every stakeholder" of the court to "fulfill its responsibility".
Human Rights Watch (HRW), meanwhile, accused strongman Prime Minister Hun Sen, himself a former Khmer Rouge cadre who defected and became premier in 1985, of trying to delay the trial.
"Hun Sen has run circles around the UN and donors while successfully denying justice for the Cambodian people," HRW's Asia director Brad Adams said.
"Cambodians now face the prospect that only three people will be held legally accountable for the destruction of their country," he added, referring to the two on trial and former prison chief Kaing Guek Eav, better known as Duch, who has been jailed for life.
Led by "Brother Number One" Pol Pot, who died in 1998, the Khmer Rouge wiped out nearly a quarter of Cambodia's population through starvation, overwork or execution in a bid to create an agrarian utopia during their 1975-79 rule.