Two former Khmer Rouge leaders Thursday began appeal hearings against their landmark convictions for crimes against humanity last year which saw them handed life sentences by Cambodia's U.N.-backed court.

"Brother Number Two" Nuon Chea, 88, and ex-head of state Khieu Samphan, 83, were the first top leaders of a regime responsible for the deaths of up to two million Cambodians to be jailed.

Cambodia received its first batch of asylum-seekers from Australian custody on Thursday, with rights groups labeling them "human guinea pigs" for an uncaring policy by Canberra to offload refugees onto other countries.

The migrants -- three Iranians and one ethnic Rohingya from Myanmar -- were flown into Phnom Penh, the capital of one of Southeast Asia's poorest nations with a weak record of upholding human rights.

At least 18 Cambodian garment workers were killed and 21 injured on Tuesday when a bus crashed into the van transporting them to work, officials said.

Photographs from the crash site showed a scene of carnage with bodies thrown from the mangled wreckage of the workers' van.

Tearful survivors on Friday marked 40 years to the day since the black-clad Khmer Rouge marched into Phnom Penh, ending a civil war but heralding a terror that killed a quarter of Cambodians and turned the capital into a ghost town.

A few hundred people, including monks and elderly regime survivors, gathered early Friday at Choeung Ek -- the most notorious of the regime's "Killing Fields" on the capital's outskirts -- burning incense and saying Buddhist prayers at a memorial stupa housing the skulls and bones of victims.

Cambodia has deported 36 Vietnamese Montagnards after they were arrested while trying to seek asylum, in the latest expulsion of a hill tribe group fleeing persecution, activists said Monday.

Scores of Montagnards, mainly Christian ethnic minorities in Vietnam's mountainous Central Highlands, have crossed the border to Cambodia in recent years to escape discrimination -- with an uptick in cases over the last few months.

A witness told Cambodia's U.N.-backed court Wednesday that Khmer Rouge soldiers slit prisoners' throats and ate their gall bladders during the 1970s, as the genocide trial of the two most senior surviving leaders resumed.

Nuon Chea, 88, known as "Brother Number Two", and former head of state Khieu Samphan, 83, face charges over the killing of ethnic Vietnamese and Muslim minorities, forced marriage and rape during the 1975-1979 regime that left up to two million people dead.

Fourteen Vietnamese hill tribe Montagnards are hiding in a remote Cambodian jungle after crossing the border to flee persecution and seek asylum, rights activists said Tuesday.

They follow in the footsteps of 13 other members of the ethnic minority group who applied for asylum in Cambodia in December, with assistance from the United Nations, after spending nearly two months camped in jungles in northeastern Rattanakiri province.

Two Khmer Rouge leaders have formally appealed convictions for crimes against humanity which saw them handed life sentences by Cambodia's U.N.-backed court.

In August "Brother Number Two" Nuon Chea, 88, and the ex-head of state Khieu Samphan, 83, became the first top leaders to be jailed from a regime responsible for the deaths of up to two million Cambodians from 1975-1979.

Two Khmer Rouge leaders were jailed for life Thursday after being found guilty of crimes against humanity, the first sentences against top figures of a regime responsible for the deaths of up to two million Cambodians.

Neither "Brother Number Two" Nuon Chea, 88, nor former head of state Khieu Samphan, 83, betrayed any hint of emotion as the sentences were handed down at Cambodia's U.N.-backed tribunal.

About 1,000 people Tuesday marked Cambodia's annual "Day of Anger" against the genocidal former Khmer Rouge regime, with black-clad students wielding hoes and bamboo sticks to mimic their crimes in the late 1970s.

The crowd, including monks and children, watched the re-enactment at the Choeung Ek "Killing Fields" on the outskirts of Phnom Penh, the site of mass graves for victims of the 1975-79 fanatical Maoist regime.