Zoo-goers were today shocked by the sudden passing of a giant panda at a Thai zoo this week.

The female giant panda Lin Hui had fallen ill on April 18 and died the following day, with zoo staff in Chiang Mai, northern Thailand, blaming old age for her sickness.

Visitor Phetdarin Wanitaroj, who had taken her son from Chonburi province to see the zoo's star attraction, said she was sad that the panda had died.

Phetdarin said: 'At first, I couldn't believe the news. But when I asked the zoo workers, they confirmed it, and I felt quite sad. My son didn't even get to see the panda before she died.'

Another traveler, Jane Chancharoen, said: 'I first saw Lin Hui before then pandemic and again about a year ago. She was so beautiful. I was looking forward to seeing her again this year with my children.'

Staff have made a memorial and laid flowers for Lin Hui near the zoo's panda exhibit.

They are currently preserving her body while waiting for panda experts from China to arrive and find the cause of her death.

Lin Hui was born on September 28, 2001 at the China Conservation and Research Centre for Giant Pandas in Sichuan province before being gifted to Thailand, along with another panda named Chuang Chuang, in 2003.

Both served as a symbol of friendship and goodwill from the Chinese government.

Chuang Chuang died of heart failure on September 16, 2019.

Lin Hui and Chuang Chuang successfully bred through artificial insemination and had a baby named Lin Ping, who was born on May 27, 2009.

Scientists are unsure of the giant panda's lifespan, but believe they live around 15 to 20 years in the wild, and around 30 years in human care, the Smithsonian's National Zoo and Conservation Biology Institute said.