Xiang Xiang has been being prepared for release for three years

Five-year-old Xiang Xiang, whose name means Auspicious, was set free from the Wolong Giant Panda Research Centre in south-western Sichuan province.

He was fitted with a global positioning device and tracking monitor so experts could check his progress, China's official Xinhua news agency reported.

Giant pandas are one of the world's most endangered species.

Only about 1,600 remain in the wild, with another 180 living in captivity.

They are threatened by loss of habitat, poaching and a low rate of reproduction.

Trained to bite and howl

Xiang Xiang, who weighs 80 kg and is 1.1 metres in height, was born in the research centre in 2001.

Officials gave Xiang Xiang a final check-up before his release

He has spent the last three years in a special training compound to prepare him for a natural habitat.

Centre director Zhang Hemin said the panda had learned to forage for food, mark his territory and fend off intruders, as well as acquiring defensive skills, such as howling and biting.

Mr Zhang said Xiang Xiang was being released now because at this time of year, there would be plenty of bamboo shoots, the giant panda's favourite food, making it easier for him to survive.

The World Wildlife Fund's representative in China, Dermot O'Gorman, told the Associated Press news agency that while Xiang Xiang's release was a significant move, it was vital to protect panda habitats.

"Fragmentation of the panda areas is a real problem," he said. "Not being able to move across the habitat because of human disturbance is a problem for pandas."

Last year China reported its most successful year for breeding giant pandas in captivity, with 25 cubs born through artificial insemination.

Sixteen of the cubs were born at the Wolong centre where Xiang Xiang has been raised.