Cambodia's Supreme Court has upheld the conviction of a former Khmer Rouge commander for the murder of three western backpackers.

The five-member Supreme Court rejected Chhouk Rin's final appeal against his conviction and life sentence for his role in the deaths of the backpackers.

The three young men from Australia, Britain and France were captured in 1994 during a Khmer Rouge attack on a passenger train in southern Cambodia. They were held for several weeks at a Khmer Rouge mountain stronghold before being killed after ransom negotiations failed.

Chhouk Rin had denied that he led or ordered the attack, but the Appeals Court in November 2003 upheld his lower court convictions on charges of terrorism, robbery and murder.

The former mid-ranking Khmer Rouge commander was not present for the appeals verdict and the Supreme Court ordered that he be arrested. He is the third former Khmer Rouge officer to be jailed in connection with the case.

Diplomats and relatives of the victims attended Wednesday's Supreme Court hearing.

Lao Mong Hay heads the legal unit of Cambodia's Center for Social Development, a pro-democracy group in Phnom Penh. He has been following the case and says it took on greater political urgency because of the international interest.

"To please a foreign plaintiff, there's been pressure from all sides for the government and the court to dispose of the case," he said.

Mr. Lao Mong Hay says most Cambodians are happy to see Chhouk Rin taken to prison. But he adds that people wonder if the government would have been as aggressive in pursuing the case if the train ambush had left only Cambodians dead.

Between 1975 and 1979, the Maoist Khmer Rouge imposed a reign of terror over Cambodia. An estimated two million Cambodians were executed or died of starvation, disease or overwork before a Vietnamese invasion force ousted the regime.

The Khmer Rouge continued to fight against the central government until 1996, when defections began to break up the movement.

Mr. Lao Mong Hay says Cambodia is still coming to terms with the period. After years of negotiations, Cambodia signed an agreement with the United Nations last year that paves the way for the trial of surviving Khmer Rouge leaders for crimes against humanity.

But an apparent lack of political will, combined with the high costs associated with the trials, have delayed proceedings.