Cambodia's Supreme Court has rejected an appeal by a former Khmer Rouge general against a life sentence for the killing of three backpackers in 1994.

Nuon Paet, was convicted three years ago of murdering the three men, who were abducted from a train during an ambush by Khmer Rouge guerrillas.

In his appeal, Nuon Paet argued that he was only a regional civil administrator at the time and that his military seniors were responsible for the attack.

Australian David Wilson, one of those killed

But the presiding judge, Khim Pon, said Nuon Paet "could not escape from his responsibilities" as chief of the guerrilla operations in the southern region of Cambodia where the Australian, Briton and French man were killed.

The Australian ambassador to Cambodia, Louise Hand, welcomed the verdict, but added her government would push for the convictions of other Khmer Rouge figures blamed for the murders.

A verdict in the retrial of another senior officer, Chhouk Rin, acquitted of the murders two years ago, has been postponed until Friday.

A third, Sam Bith, was arrested in May this year in connection with the killings, and is in detention awaiting trial.

Denial of responsibility

Nuon Paet told the court that Chhouk Rin, Sam Bith and a field commander called General Veth Vorn, who apparently died in the mid-1990s, were to blame for the murders.

"I didn't order the killings," he said.

But Jean-Claude Braquet, the father of one of the men who died, told the court the defendant should be held responsible.

"Nuon Paet made two mistakes. One, he was responsible for the Vine Mountain region, and second, he demanded the ransom from the government."

Jean-Michel Braquet, David Wilson, and Mark Slater were killed after a botched attempt to pay a ransom for their release from the Vine Mountain rebel base in the southern Cambodian province of Kampot.

They had been kidnapped in an ambush of a train in July 1994, during which at least 10 Cambodians were killed.

Doing enough?

Judge Khim Pon said the crimes under Nuon Paet's command were "vicious and barbaric".

But there is continuing international concern that Cambodia's government is not serious about its commitment to bring former Khmer Rouge leaders to trial.

Negotiations between the UN and the Cambodian Government to set up an international tribunal broke down in February, after UN officials said they were concerned the planned hearings would not meet international standards of justice.

But last month Cambodia's Prime Minister Hun Sen agreed to work with the UN to revive talks on the issue.