The first panda to be released into the wild after being bred in captivity has been found dead in forests in southwest China.

Xiang Xiang was found in February on snow-covered ground in the forests of Sichuan province in China's southwest, the Xinhua News Agency said.

It is believed he suffered fatal injuries after he fell from a tree while being chased by other pandas. He had undergone three years of training on how to survive in the wild but he lasted less than a year.

"Xiang Xiang died of serious internal injuries in the left side of his chest and stomach by falling from a high place," Heng Yi, an official from the Wolong Giant Panda Research Centre in Sichuan, said in a telephone interview.

"The scratches and other minor injuries caused by other wild pandas were found on his body," he said.

"So Xiang Xiang may have fallen from trees when being chased by those pandas."

Heng said that the long delay in announcing Xiang Xiang's death was attributed to the need for a full investigation.

Before he was released, Xiang Xiang did learn how to build a den and defend himself, but his death suggests that wild pandas are reluctant to accept outsiders who have been bred in captivity.

"We are all sad about Xiang Xiang, but it doesn't mean the project has failed," Zhang Hemin, the center's head, was quoted as saying by Xinhua. "The lessons we have learnt from what happened to Xiang Xiang will help us adapt and improve the project."

The 176lb (80 kilo) male panda was released from Wolong in April 2006. Xiang Xiang, whose name means auspicious, learnt how to build a den, forage for food and mark his territory, experts at Wolong have said. He also developed defensive skills like howling and biting.

According to Li Desheng, deputy director of the Wolong centre, Xiang Xiang's case proves that wild panda communities are reluctant to accept male outsiders.

"We chose Xiang Xiang because we thought that a strong male panda would have a better chance of surviving in the harsh natural environment," Mr Li was quoted as saying.

"But the other male pandas clearly saw Xiang Xiang as a threat. Next time we will choose a female panda."

State media reported last year that Xiang Xiang hesitated for a second when the door of his cage was opened, then scampered off into a nearby bamboo forest where he was tracked by a global positioning device attached to his collar.

He has been buried at the foot of a mountain, about 13 kilometres (8 miles) from the Wolong centre, Li said.

There are only about 1,600 wild pandas in the mountain forests of central China - the only place in the world they are found, and more than 180 live in captivity.

Pandas are threatened by loss of habitat, poaching and a low reproduction rate. Females in the wild typically have a cub once every two to three years.