Adelaide, Jun 29 (IANS): Australia's oldest captive Sumatran tiger has died at the Adelaide Zoo at the age of 22 after veterinarians decided to euthanise her due to critical age-related conditions.

Kemiri was born at Sydney's Taronga Zoo before she was transferred to Adelaide.

A senior veterinarian at the Adelaide Zoo, Ian Smith, said she lived a long and happy life before kidney troubles and arthritis took a toll, forcing vets to undertake the procedure late on Wednesday evening, reports Xinhua news agency.

"For a number of months, Kemiri had been suffering from a number of age-related conditions which the veterinary team had been treating but over the past week her condition deteriorated," Smith said in a statement on Thursday.

"The veterinary team decided that further medical treatment would not improve Kemiri's quality of life. The difficult decision was made to humanely euthanise her, and although this is a sad loss for Adelaide Zoo, it was the best thing to do for Kemiri."

Smith said Kemiri lived a life almost twice as long as what's expected for Sumatran tigers in the wild.

"The average life expectancy for Sumatran tigers in the wild is about 12 years - and in captivity about 20 years - so to reach 22 is really positive," he added.