KUALA LUMPUR - MALAYSIAN police said on Monday they are investigating the death of a French man who died after an altercation with four French citizens in a yacht off the tourist island of Langkawi.

Mr Serge Castan, 49, was travelling with four other French nationals - his girlfriend and her sister, brother-in-law and mother - who were released on police bail last Friday after being held for two weeks, they said.

Langkawi police chief Mohamed Ali Jamaludin said the group were tourists who arrived in Langkawi on a yacht which they had sailed from nearby Penang island.

He said initial investigations indicated that the five were having a private party out at sea on their yacht, La Bulle, when an argument involving the dead man broke out in the early hours of the morning.

'He started becoming aggressive and they said that they had to tie him up to keep him under control. They said they had been drinking,' Mr Mohamed Ali said.

The group reached the Langkawi yacht club at 9 am on October 24 and the unconscious man was taken to a nearby hospital where he later died, he said.

'The police were only alerted about the incident after the man was brought to the hospital, when the doctor found some stab wounds on his hands and some marks indicating that his hands were bound,' Mr Mohamed Ali said.

'We brought all four of them to the police station to record their statements. They spoke only French so we had trouble communicating and did not really know what had transpired. One of them was also injured.'

The four were released on police bail, which does not require any bond to be paid, while waiting for post mortem results to be completed. Malaysian police can hold suspects for up to two weeks before having to lay charges.

'After the cause of death has been determined then we can consider a charge against them, depending on the outcome of the post mortem,' Mr Mohamed Ali said.

A French diplomatic source confirmed that the four citizens - who cannot be named - were released on November 7 after spending two weeks in police custody.

'They committed themselves to go and be present in court, either as witnesses or defendants if charges are brought against them,' he said, adding he was not aware if they have left the country.