The family of an elderly Australian man who died onboard a flight where the air conditioning failed and temperatures soared above 95 degrees may have to pay $20,000 to bring his body home.

The man's brother, who was traveling with him, told family members Air France had requested the money Wednesday.

Arthur Hesket, 85, from Western Australia, had been on a cruise in Germany on his first trip to Europe when he suffered as suspected heart attack or stroke onboard the Air France/Qantas flight.

"We are obviously very upset," his step-daughter Karina, who was on vacation in New York at the time, told news.com.au.

"At this point all arrangements are being attended to in Romania."

The plane was forced to make an emergency landing in Bucharest, Romania, where the Australian Consulate General and Australian Embassy were assisting the man's family, a spokeswoman for the Department of Foreign Affairs said.

Passengers were furious the Boeing 777 departed on the flight from Paris to Singapore in the first place given the fact the air conditioning wasn't working.

Melbourne lawyer Ian Dunn, who was on vacation with his wife, said the plane was unbearably hot.

"The really awful thing was that it is quite possible that the heat on the plane when we first got on — which probably lasted about an hour and a half — may well have had some impact on this man dying," he said.

Dunn, who was sitting a few rows behind, said the first he knew of any incident was when announcement was made asking if there was a doctor onboard and several people came forward. The plane made an emergency landing in Bucharest but the man died before or soon after it arrived.

About 360 passengers were left on the flight for more than five hours without air conditioning before returning to Paris.

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