Giant panda Lin Hui, the star attraction at Chiang Mai Zoo, died on Wednesday morning. She was 21 years old.

The zoo announcement said Lin Hui had first shown unusual symptoms on Tuesday. Zoo officials had also consulted Chinese experts. Despite their best efforts, she died on Wednesday morning.

The cause of her death was still unknown. Further details were expected to be announced later in the day.

Lin Hui was born in China on Sept 28, 2001, in Chengdu, Sichuan province.

Lin Hui was sent to Chiang Mai Zoo on Oct 12, 2003, as a goodwill ambassador between China and Thailand.

She was an instant star attraction. Lin Hui was scheduled to return to China this year.

Chiang Mai Zoo celebrated the giant panda's 21st birthday in September last year.

More than 7.4 million visitors had dropped by the zoo since October 2003 to see Lin Hui and Xuang Xuang, the two giant pandas on loan from China.

The male panda, Xuang Xuang died at Chiang Mai Zoo on Sept 16, 2019.

Giant pandas typically have a lifespan of 15 to 20 years in the wild, and up to 30 years in captivity.