A young Russian man has been found dead with severe injuries in a ditch at Phuket's Karon beach, and police believe he was killed elsewhere and his body dumped there. 

He was wearing only a pair of shorts and was found in the ditch near the Naga statue along the road fronting Karon beach, police said.

The discovery of his body was reported to police about 1pm on Tuesday. 

The dead man had multiple injuries, including wounds near his eyes, bruising around his left ear and deep cuts on both arms. It appeared he had been hit with a hard object.

Doctors estimated he had been dead for at least 8 hours before his body was found.

A travel bag containing a passport, other documents and a Macbook laptop was found near the body.

Police identified him only as Ilia, and said he was Russian. He arrived in Phuket on Jan 24 this year, entering Thailand with his wife. His 90-day visa expired on July 22 and he extended it by going to Malaysia and back via Satun. 

Investigators said it appeared he had been killed elsewhere and his body later dumped in the ditch. They were examining recordings from security cameras in the area for clues. The body was sent for post-mortem examination to find the cause of death.

Media reports said the man was 27 years old.