Sam Bith appears in a Phnom Penh court December 13, 2002.

Former Khmer Rouge commander Sam Bith, who was serving a life sentence over the kidnapping and murder of three Western backpackers in 1994, has died at aged 74.

According to his wife, Khem Ri, Bith died on the night of February 15. He had been treated for high blood pressure and diabetes at a hospital in Phnom Penh since last month, and drifted in and out of consciousness in his last 10 days, his wife said.

Sam Bith was sentenced to life in prison in 2002 by Phnom Penh municipal court over the abduction and murder of Australian David Wilson, Briton Mark Slater and Frenchman Jean-Michel Braquet.

The three were kidnapped after the train they were traveling in was attacked between Phnom Penh and the southern port city of Sihanoukville in 1994.

Thirteen Cambodians also died in the attack, and the Westerners were held for two months by Khmer Rouge rebels before ransom negotiations collapsed and they were killed by their captors.

Sam Bith had denied any involvement in the killings, saying he was hospitalized in Thailand at the time of the kidnappings, and that Khmer Rouge leader Pol Pot had removed him from his position.

The murders triggered an international outcry and opened a long and emotional legal wrangle.

Two other former Khmer Rouge members, Nuon Paet and commander Chhouk Rin, are serving life prison sentences for their role in the killings. (AFP)