A bodyguard for Prime Minister Hun Sen yesterday told the Khmer Rouge tribunal how he jumped into the Mekong River to escape execution during his testimony on the oppression of the Cham Muslim people during the reign of the Pol Pot regime.

Van Mat, 62, said that he drove his commune chief to a meeting in late 1978, only to overhear that Cham and other “traitors” in the Eastern Zone were to be purged.

“Angkar gave the instruction to smash 100 per cent of the Cham,” he said.

Ke Pok – whom the witness said had also been called “Pol Pok”, and who was later made a brigadier-general in the Royal Cambodian Armed Forces after defecting from the Khmer Rouge – presided over the meeting, the court heard.

Mat’s village of Chumnoek, on the south bank of the Mekong, was then evacuated. Up to 500 men, women and children the vast majority of them Cham were herded onto boats at night.

According to the witness, only one man dared protest – he was “arrested and beheaded and thrown into the river”.

When the boats arrived at Stung Treng in the Central Zone, women and children were taken away, while the men’s hands were tied. “I told my friends the situation could be dangerous for us . . . so we jumped into the water,” Mat said.

The witness said guards on the boats, armed with AK-47s, fired bullets into the water, but all missed their targets. Mat said he then returned to his mobile brigade in Chumnoek, where he persuaded others to flee into the forest and rebel with a handful of weapons they recovered from wells.

“If we did not retaliate, we would be killed,” he said.

The witness then told the court he combined forces with Kun Kim – who is today the Royal Cambodian Armed Forces deputy commander-in-chief – to resist the Khmer Rouge.

Victor Koppe, defence lawyer for Nuon Chea, asked the witness if his boss, Prime Minister Hun Sen, had ever told Mat he was once a Khmer Rouge deputy regiment commander for Sector 21.

“Did he ever tell you [if] his regiment had any role in crushing the Cham rebellion in late 1975?” Mr Koppe asked. “No he did not,” the witness replied.