This is the moment a sun bear waved at zoo-goers in Thailand amid questions over 'humans in bear costumes' in China.

Footage shows the sun bear standing upright on its hind legs inside its enclosure as it greeted visitors at the Tha Lat Open Zoo in Nakhon Si Thammarat province on Wednesday.

The scene comes amid suggestions that similar sun bears in China were merely people in bear suits being passed off as wild animals.

Footage of that Malayan sun bear named Angela, taken at the Hangzhou Zoo in China's eastern Zhejiang province, sparked bizarre theories among Chinese locals due to its slender appearance and wrinkled skin that looked uncannily like a person in an ill-fitting costume.

The zoo wrote online, speaking from Angela's perspective: 'Some people think I stand like a human, and it seems that you don't understand me that much.

'Previously, some tourists thought that I was too tiny to be a bear. I have to emphasize again: I am a Malayan sun bear! Not a black bear! Not a dog! A sun bear!'

Sun bears are the smallest bear species in the world, and they are found in the tropical rainforests of Southeast Asia, including Thailand. It gets its name from a distinct cream-coloured patch on its chest.

Sun bears primarily have an omnivorous diet, which includes fruits, insects, small vertebrates, honey, bird eggs, termites, and even occasional vegetation such as young leaves and bark.