Police investigating the death of an Australian backpacker who fell to his death form a hotel on a Thai island have found sex drugs in his room.

Billy James Simmons, 22, had arrived in Phuket with several friends earlier this month before partying in the notorious red-light district Patong Beach.

He was due to return to Australia on May 28 but was found dead lying face down on a footpath below his 11th floor room at the Royal Paradise Hotel & Spa on Tuesday night, May 17.

Shocked security guard Wongthatsatham Santi discovered Billy's lifeless body before calling paramedics but they were unable to revive him.

Police arrived at the scene shortly afte to investigate. They said they found a half-empty bottle of Whisky in Billy's room as well as an empty bottle of Chang beer. They also discovered a number of boxes of opened sex drugs, which they believe Billy had used.

Local massage girls working at a shop next to the hotel said they recognised Billy because he walked past them every day and was 'often drunk'.

They told police they also suspected he had used the drugs.

Masseuse, Khun Wan, said: 'I often saw him both in the morning and in the evening and he always looks like he was drunk. It's a shock that he has died.'

Police Lieutenant General Salid said officers believe that Billy had been staying alone in his hotel room on the night he died. They believe he was drunk and plunged from the balcony.

The policeman added: 'Initial investigations suggest that the tourist had been drinking alcohol before he fell and died. We are also interviewing his friends to find out if there are any other reasons involved.

Police recovered a number of prescription medications from Billy's hotel room, including Viagra.

Police Lieutenant General Salid added: 'There was no sign of a struggle in the room. From interviewing the friends, they said he had been out partying with Billy then took him back to the room and left him there. Then he later fell from the balcony.'

Officers said that the Australian Embassy had been informed of Billy's death. His father is believed to be flying out to the island to collect Billy's body so it can be repatriated to Austrlia.