Bangkok - The body of a British national who was murdered on his yacht earlier this week was found Friday floating in Thai waters offshore of Satun province, media reports said.

A Thai search team found the body of Malcolm Robertson, 64, about 10 kilometres off Ravi Island in the Andaman Sea, about 800 kilometres south of Bangkok, The Nation online service reported.

Robertson was killed on Monday while holidaying on his yacht with his wife Linda. His body was thrown overboard.

Thai police arrested three Burmese migrant fishermen as the key suspects in the murder, who can now be prosecuted as the body of Robertson has been found.

The Myanmar nationals have confessed to slitting Robertson's throat after he caught them climbing on to his moored yacht in an attempt to steal an inflatable dinghy.

The assailants were reportedly trying to flee their employment on a Thai fishing boat. (dpa)