A female giant panda seen here a few months ago while she was healthy has died after falling ill at a zoo in Thailand.

Lin Hui, 21, passed away at the Chiang Mai Zoo this morning April 19 after she became severely sick the day before.

Zoo vets monitored her condition and consulted specialists in China, but despite their best efforts, they could not save the giant panda.

Zoo director Wuthichai Muangman said the cause of death has not yet been identified, but believes it was due to Lin Hui's age.

Lin Hui was still in good health when last seen by local media on Valentine's Day.

She 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 an offspring 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.