The world's oldest known Sumatran orangutan has died in an Australian zoo aged 62, leaving behind 54 descendants, wrote BBC.

Puan, described as the "grand old lady" of Perth Zoo, was euthanised on Monday due to age-related complications.

She had been at the zoo since 1968, and was officially recognised by Guinness World Records as the oldest of her species in 2016.

A critically endangered species, Sumatran orangutans rarely reach age 50 in the wild, the zoo said.

Believed to have been born in a jungle in Sumatra, Indonesia, in 1956, Puan left an "incredible legacy" of 11 children and a total of 54 descendants across the US, Europe and elsewhere, the zoo said.

"Her genetics count for just under 10% of the global zoological population," primate supervisor Holly Thompson said.

"She did so much for the colony at Perth Zoo and the survival of her species."

Some of Puan's descendants have been released back into the wild in Sumatra, the zoo said.

According to the World Wildlife Fund, there are only about 14,600 Sumatran orangutans.

Puan's chief zookeeper wrote an obituary published in The West Australian newspaper on Tuesday.

"Over the years Puan's eyelashes had greyed, her movement had slowed down and her mind had started to wander," Martina Hart wrote.

"But she remained the matriarch, the quiet, dignified lady she had always been."