Sam Bith, the former Khmer Rouge commander arrested in connection with the murders of three Western backpackers in 1994, has been formally charged.

Appearing in court in Cambodia's capital Phnom Penh, Sam Bith was charged with kidnapping, conspiring in premeditated murder, terrorism and robbery.

We are very worried about his health

Police officer

Sam Bith, 69, looked pale and unwell. A police officer said he suffered very high blood pressure overnight and two doctors had been assigned to look after him.

The charges relate to a July 1994 ambush of a train by former Khmer Rouge rebels. At least 10 Cambodians were killed during the attack.

The three foreigners - Australian David Wilson, Frenchman Jean-Michel Braquet and Briton Mark Slater - and several Cambodians were taken to the nearby Vine Mountain rebel base in the southern Cambodian province of Kampot.

They were killed after negotiations for their release and the payment of a $150,000 ransom broke down.

The Khmer Rouge commander of Vine Mountain, Nuon Paet, was jailed for life in June 1999 for his role in the affair.

International concern

During his trial, Nuon Paet said that his superior officer, Sam Bith, had ordered the tourists killed.

Sam Bith was a powerful regional commander for the Khmer Rouge and former deputy to its military head Ta Mok.

The arrest comes amid 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.

Sam Bith, who was made a general in the Cambodian army after defecting from the Khmer Rouge in 1996, was arrested in the north-western province of Battambang on Wednesday.

A warrant was issued for his arrest in 1999, but police said they had been unable to find him.

His arrest followed the publication in a Thai newspaper of reports on his lavish home in Pailin, western Cambodia.

A journalist visiting Pailin saw Sam Bith and interviewed the police chief living next door.