JAKARTA: Indonesian conservationists said on Friday they had caught red-handed a 92-year-old man who had admitted to killing dozens of critically endangered Sumatran tigers over a lifetime of hunting.

"We caught him Thursday while he was sailing a traditional wooden boat in a river in Kuala Cinaku with evidence of skin, skull and 8.3 kilos of bones from a tiger," Iwin Kasiwan, from the natural conservation agency in Riau province, Sumatra, told AFP.

The man, named Wiryo, told conservationists that he started hunting tigers for a living when he was 17 on Java island. He moved to Sumatra in 1960 as the population of Javan tiger decreased.

"According to him, he has killed more than 50 Sumatran tigers in Riau province alone," Kasiwan said, adding it could see the 92-year-old jailed for up to five years.

Wiryo explained that he managed to sell the tiger parts in Singapore.

There are fewer than 400 Sumatran tigers left in the wild and their increasing contact with people is a result of habitat loss due to poaching and deforestation, according to conservationists.