An Australian man has been beaten to death in a savage bar fight in Thailand.

Benjamin Robb had only recently arrived in Thailand when he went to the popular Ruby lounge at Pattaya, about 150km from Bangkok, on Friday night.

It was at the Ruby bar that witnesses say the 43-year-old was savagely bashed by a man who had been at the venue with at least four other people.

It is alleged an American tourist repeatedly punched Mr Robb to the face and threw him across the bar, before stomping on his head.

Mr Robb was rushed to the nearby Pattaya Memorial Hospital, but despite treatment he died in the early hours of Saturday from injuries including internal bleeding.

The American national allegedly left the bar but later surrendered himself to police.

A Department of Foreign Affairs spokesperson confirmed it was providing assistance to family members in Thailand.

Eyewitnesses said both men had been drinking heavily in the afternoon and appeared intoxicated when the fighting broke out.

The Ruby Club, in a statement, said the altercation had been brief and had left the Australian unconscious. The American, the statement said, was expected to be held in jail for at least 10 days before an initial court appearance.

Thai police said they would be carrying out a thorough investigation.