Police are probing the mystery death of a tourist in a hotel in Thailand.

The holidaymaker was discovered by a maid cleaning the rooms of the property on the backpacker haven of Khao San Road in Bangkok on January 6.

The male tourist was seen lying lifeless on the floor. He had no belongings except for the clothes he was wearing and investigators said there were no signs of assault at the scene.

Staff said the 'homeless' man was not a guest and had repeatedly been sneaking into the hotel, trying to stay in unoccupied rooms.

Police Captain Surawit Mangngam of the Chana Songkhram district station said: 'Initially, we have entered his information into the CIR system to determine his identity and nationality, and fingerprint comparisons are underway. The results are not yet known. He is estimated to be around 50 years old.

'I was notified by hotel staff at around 10 am. They were preparing to clean the room for incoming guests when the body was discovered.

'The body was not naked. He was wearing clothes but no shoes. There were no signs of assault or external injuries.'

'Before the New Year, there was a report that he had been sleeping near rubbish bins, and volunteers were called to take him to the hospital, but he refused.'

The policeman said that officers were reviewing CCTV footage to determine how the man had entered the building.

A receptionist at Villa ChaCha Hotel said: 'The dead man was not a hotel guest and had been sneaking in to stay, seemingly like a homeless person.

'He had previously entered the hotel twice, and each time we asked him to leave. We tried asking who he was and where he came from, but we couldn't communicate with him clearly. He appeared mentally unstable, spoke incoherently, and had no identification documents. We don't know who he was or what nationality he was.

'The room was on the fourth floor. The last guest checked out on January 3, after which the room was vacant. This morning, a housekeeper opened the door to clean the room in preparation for new guests and found him lying dead.

'He did not climb into the building. He walked in through the door, as there was no security stationed at the front of that building, so no one knew when he entered. There was no damage to hotel property in the room, and he had no injuries.'

Authorities said the man's body has been taken to Vajira Hospital to determine the cause of his death.

Khao San Road in Bangkok is a backpacker hub popular for cheap hostels, affordable street food, tattoo parlours and a bustling nightlife.