Thousands of bears are being kept in "torture chambers" to produce bile for the traditional Chinese medicine market, wildlife campaigners say.

The London-based World Society for the Protection of Animals (WSPA) has published the results of a two-year undercover investigation into 12 bear bile farms in China.

The survey has been released to coincide with a major international conference on endangered species.

The harness used to secure bile bears

The trade in bile, which is used in many traditional ointments, as well as shampoo, wine and eye drops, will be debated at the Convention on International Trade in Endangered Species (Cites) when it meets in Nairobi between 10-20 April.

The WSPA is calling on bile farms to be closed down.

Its report documents how thousands of bears are kept in horrific conditions in hundreds of farms across China, producing approximately 7,000 kilos of bile every year. The society fears China is planning to register some of its bear bile farms with Cites.

Such a move would allow the Chinese to circumvent the existing international ban on trade in bear parts.

Cites

Cites was established in 1975 by the United Nations to regulate the trade in wildlife 150 countries signed the treaty, including China

And WSPA say it would also hasten the demise of bears in the wild, with many taken each year to restock the farms and encourage the continued development of this "farming".

Top officials from the Department of the Environment, Transport and the Regions are to attend the Cites conference.

Jonathan Pearce, WSPA campaigns director said: "We're calling on Cites to reject any attempts by China to legitimise its bear farms.

"The farming of bears for their bile should be brought to an end as soon as is feasible and Cites should make all efforts to maintain the ban on international trade in bear parts and derivatives."

Bear bile bare facts

WSPA say 7,000 bears are in bile farms 247 official bear bile farms in China Estimates of wild bear populations in China range between 20,000 and 60,000

WSPA investigators found that almost every farm they visited bought bears taken from the wild.

The charity said animals were surgically mutilated, often by untrained workers with no veterinary skills, and "milked" each day for their gall bile.

Bears had to endure the most appalling levels of cruelty and neglect.

Many were wounded and scarred due to the friction caused by being kept in tiny metal cages which were just about big enough for them to fit into and where they are unable to stand straight.

Cages were suspended above the ground, with bears having to suffer a constant stream of bile seeping from their stomachs, where an open wound allowed workers to insert a tube or piece of metal to "tap" the bile, the report states.