PHUKET CITY police are looking into the mysterious death of a man who may have been the victim of a heart attack - or a deliberate drugging and theft.

The first aim of the investigators is to identify the man, about 60, who died naked with his right hand clutched to his heart in a room at a hotel in Vichit, south of Phuket City, this morning.

The man's body was discovering in the room about noon when staff at the T. Songsan Hotel knocked on the door, received no answer, and opted to open it.

Inside they found the man's body on the bed and the ceiling fan still turning. Nearby were two bottles of green soft drink, both opened and containing straws, with one half-drunk and the other almost full.

The floor in the shower was still wet.

The woman who was on duty at the hotel's reception desk told police that a couple checked in about 9.40am, and they only wanted to stay an hour. The man paid 120 baht for one hour in the room, and the receptionist remembered him pulling out his wallet.

There was no wallet found in the room, although the man was still wearing a wristwatch. The man's companion, the receptionist said, was a tall woman, between 165 and 170 centimetres, with a long nose, aged about 45.

Police are keen to talk to the woman and are now checking the registration of the Honda motorcycle and its illegal sidecar attachment on which the couple arrived.

The green soft drink is being checked for the presence of drugs. Locals around the hotel are being asked whether they know the man.

His body is now at Vachira Hospital in Phuket City.