China has introduced six giant pandas into a "semi-wild" environment on Wednesday. This is claimed to be one of the most ambitious attempts so far to build up the endangered population with captive-bred bears.

Celebrities including retired basketball star Yao Ming attended the ceremony in Dujiangyan, Sichuan Province, to mark the relocation of the bears.

Celebrities including retired basketball star Yao Ming attended the ceremony in Dujiangyan, Sichuan Province, to mark the relocation of the bears.

Yao Ming said, "I think the most important thing is to keep the balance between humans and nature. We have been talking about it for many years but it is never an easy thing to do. It is the thousand-year-old central thinking in the Chinese Confucian culture."

Chengdu's researchers hope a phased approach will bring greater success. The six giant bears will be set loose for "training" in a controlled rehabilitation area of 20 hectares in Dujiangyan's "Panda Valley" that is still under development.

The animals have been selected according to their health, behaviour and genetic diversity from the 108 pandas at the Chengdu Panda Base.

They are all adolescents - ages two-to-four - a time when scientists hope they will be strong enough to fend for themselves, but still young enough to adapt.

Those who respond well to foraging and other skill training will eventually be released into the nature reserve.

It is hoped that as they mature and breed, they will produce offspring fully accustomed to living in the wild.

Once the 300 million yuan Dujiangyan facility is completed, it is expected to host more than 30 pandas at a time.

The goal is to release 100 animals into the wild over the next 50 years. The researchers involved say patience will be one of the biggest keys.