An Australian boxing champion is in a coma after he was found next to the body of his dead friend and fellow boxer at a hotel in Thailand.

Pattaya police told the ABC that Muay Thai fighter Jayson Tonkin and British fighter Joshua Goldstone checked into a hotel in Pattaya on Tuesday and were supposed to check out the following day.

On Tuesday night, hotel staff heard a man shouting for help and called local police.

When they arrived, they said they found Goldstone, 21, dead on the floor at the back of the room and Tonkin, 27, in a state of intoxication and panic.

He was taken to a nearby hospital, where he remains in a coma.

Police did not detect any signs of struggle but found cannabis, white powder and a small glass tube.

They are still waiting for lab results.

Police say there are no charges against Tonkin, but once he is better, he will be questioned by authorities.

Drug possession can carry hefty sentences in Thailand, depending on the substance.

Tributes have begun to flow on social media for Goldstone.

"Shocking news and so sad. You will be missed by many people, my condolences go out to your family and friends. Rest easy bro," a friend wrote.

Another wrote: "RIP Joshua. You will be in everyone's memory."

A third described him as a "sweet … fun man".

"What a waste of a lovely life. I'm gutted".

Jayson Tonkin, also known as "The Dingo", is a middleweight Muay Thai fighter from Manly in Sydney.

He moved to Thailand as a teenager in 2012 and had his first fight at just 15.

He was due to fight WBC world middleweight champion Tengnueng Sitjaesairoong last month, but the event was cancelled due to monsoonal rain.

The Department of Foreign Affairs and Trade has confirmed it is providing consular assistance to an Australian man hospitalised in Thailand.