Grieving tourists wrote farewell notes as they mourned the death of a beloved giant panda at a zoo in Thailand.

Footage shows visitors writing their goodbyes to female giant panda Lin Hui, 21, on panda-shaped paper sheets stuck to a message board at the Chiang Mai Zoo on April 27.

The zoo's panda exhibit was opened today to visitors who wanted to pay their respects to Lin Hui. Memorial displays were also set up at the zoo entrance as well as inside her enclosure.

A mourning ceremony led by monks was held yesterday with local officials and zoo staff attending.

Wuttichai Muangman, Chiang Mai Zoo director, said: 'The entire zoo is saddened by the loss of Lin Hui, but we are heartened by the support and love shown by the visitors grieving with us.'

He added that they are still awaiting a panda expert from China to find the cause of Lin Hui's death, though an arrival date has not yet been settled. Lin Hui's body is currently being preserved at the zoo.

Wuttichai said the public will be updated as more information becomes available.

Lin Hui fell ill on April 18 and passed the following day. Zoo staff have blamed her age for the sudden death.

She was born on September 28, 20001 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 an offspring named Lin Ping, who was born on May 27, 2009.

Scientists are unsure of the giant panda's lifepsan, 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.