An Australian tourist has been found dead by shocked passengers at an airport in Thailand.

Gerard Wohlmuth, 82, had just landed for the first day of a holiday when he began feeling ill at the Suvarnabhumi International Airport in Bangkok on September 5.

He lay down on a bench to rest before planning to catch a taxi to his hotel but lost shortly after consciousness.

Concerned passengers reported the incident to the police later in the evening, when they noticed an already stiffening Gerard lying unresponsive.

Airport police officers said they received a report at 8 pm and arrived at the scene, where the octogenarian - wearing a black shirt, jeans, and gray sneakers - was lying on his back on the leather seats.

Airport officials believe the man had arrived on an afternoon flight, but decided to rest there when he felt lightheaded before passing away.

Police suspected Gerard had died of natural causes, estimating he had been dead for at least three hours. They have cordoned off the area for further investigation.

The body of the Aussie, who was born in Korneuburg, Austria, was taken to the Institute of Forensic Medicine to determine the cause of his death.

Officers said the Australian Embassy has been informed of Gerard's passing and they have contacted his relatives.