SINGAPORE - Omar, a white tiger at the Singapore Zoo, has died, Wildlife Reserves Singapore (WRS) said on Thursday (June 8).

"We are deeply saddened by the passing of our senior white tiger Omar yesterday (June 7)," WRS said. "An icon of Singapore Zoo in his own right, he enthralled guests with his majestic presence."

The tiger, who was nearly 18 years old, was closely monitored for the last three years as he developed melanoma, a type of skin cancer, and as his joints degenerated, WRS said.

A team of keepers and veterinarians had been providing supportive care to him for the past few months to ensure its quality of life was maintained.

But due to his worsening health, the "difficult decision" was made to euthanise him, WRS said.

Omar was born in Indonesia's Taman Safari and arrived in Singapore Zoo with his two sisters Winnie and Jippie on April 6, 2001, when they were 19 months old.

They mauled a Malaysian contract worker, Nordin Montong, after he deliberately climbed into the tiger exhibit in 2008.

Omar would have turned 18 years old in September. Jippie died in 2012 and Winnie in 2014.

In the wild, tigers have an average lifespan of between 10 and 15 years, while those under human care live for 16 to 20 years on average.

"We will miss Omar, and our thoughts and appreciation go especially to his caregivers, who for so many years took such great care of him,"WRS said.

Singapore Zoo is now home to two white tigers, Pasha and Keysa.

The four-year-old siblings arrived from Batu Secret Zoo in Indonesia on Jan 15, 2015.