Local media said he had died of natural causes in hospital in Bangkok on Saturday. His age was variously put at 89 or 90, although some sources gave his date of birth as August 17, 1923, making him 88.

Chaleo was ranked 205th on the Forbes list of the world's wealthiest people, with a fortune it put at $5 billion.

Born into a Chinese immigrant family, he never flaunted the wealth he accumulated and avoided publicity. According to Thailand's Nation newspaper, he had not given a media interview or made any public appearances for 30 years.

The Nation said it had interviewed his son, Saravudh, as part of a multimedia series to run next month.

Saravudh recalled how his father developed the Red Bull brand at home and abroad after his small pharmaceutical company started producing energy drinks in the 1970s.

"While the market leader of the energy-drink market mainly targeted the capital, Red Bull pushed into the provincial market first, gaining a foothold by distributing free samples to truck drivers," he said.

Only then did he market it in the capital, Bangkok, with brand-building that was quite novel for Thailand at the time, before going international with Austrian partner Dietrich Mateschitz in the mid-1980s.

Mateschitz, who had discovered the powers of Red Bull as a cure for jet lag, is now number 193 on the Forbes list.

Chaleo never had the benefit of higher education but his son said he studied English and law by himself. His acumen and experience led governments to turn to him for help and he had sat on health committees and advised the prime minister.

The Red Bull brand has been promoted internationally through a Formula One racing team and in the United States by soccer team the New York Red Bulls.

(Reporting by Viparat Jantraprap; Additional reporting and writing by Alan Raybould; Editing by Ron Popeski)

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