A former top Khmer Rouge commander is on trial in Cambodia for the 1994 kidnappings and murders of three Western tourists. But the proceedings were cut short when the defendant, Sam Bith, fell ill and the judge postponed the trial.

The presiding judge at the Phnom Penh Municipal Court halted the trial of Sam Bith shortly after it opened. Noting the defendant was having trouble standing while making his statement, the judge ordered the defendant returned to prison for medical treatment, despite his pleas that he be allowed to continue.

Sam Bith is the most senior Khmer Rouge commander charged in the case. The incident occurred while the Khmer Rouge was conducting a guerrilla war after losing power in 1979 and before negotiating an amnesty with the government in 1998.

Prosecutors say that Mr. Bith and two others orchestrated a 1994 ambush of a train in which 13 Cambodians died and three Western tourists were kidnapped and held for months - before being killed. In connection with the crime, Khmer Rouge general, Nuon Paet, was sentenced to life in prison in 1999 and Chhouk Rin was convicted last September, but is living free pending an appeal.

Mr. Bith's lawyer says his client had been removed from his position as regional Khmer Rouge commander of the area where the ambush took place and that he was in a hospital receiving treatment at the time of the crime. He defected to the government in 1996 and became a two-star general and adviser to the Defense Ministry.

Sam Bith was charged for his involvement in the murders in 1999, but he eluded capture for more than two-years. His arrest last May at his home in northwestern Cambodia prompted more than 100 former rebels to issue a statement attesting to the former commander's innocence.

His supporters included former Khmer Rouge ideological leader and Pol Pot confidant, Nuon Chea, also known as "Brother Number 2", who made a surprise appearance in court. The ailing Nuon Chea traveled to Phnom Penh by ambulance from the remote border area of Pailin. It is one of a few visits to the capital since his defection to the government in 1998 and he plans to testify to the innocence of his former subordinate.

The court has ordered Sam Bith, who suffers from high-blood pressure and diabetes, to return to the court on Friday with a doctor.