Endangered bears kept in cramped metal cages on bile farms in Vietnam are dying at a rate of two a day, a MailOnline investigation has found. More than 700 Asiatic black bears, over a third of those held in captivity in Vietnam, have allegedly been butchered in the past year alone – with up to four bears inexplicably killed in one day on some farms. Farmers claim the extinction-threatened bears are dying from disease and old age – but sources say owners are killing them to 'extract the last ounce of blood' and selling their body parts to make Chinese medicine. Barbaric: A desperate moon bear with a left paw chopped off reaches out for help from its tiny rusty metal cage at the Cau Trang bear farm in Halong Bay, Vietnam . Metal coffins: The inhumane cages where tortured bears are forced to live in as they await death. The Vietnamese government faces a race against time to get them to a sanctuary in Tam Dao national park 120 miles away run by British charity Animals Asia . Confronted: The owner's son hides his face from MailOnline man at the Cau Trang bear farm in Halong Bay. He angrily told our man: 'You have no right to interfere in our business … If you take my picture I will sue you' The paws, meat and gall bladders of the 'moon bears' – named after the yellow moon-shaped crescents on their chests – are sold for the equivalent of £625 a bear and smuggled to China for use in traditional medicine, sources familiar with farm operations told MailOnline. Insiders say the bears are being massacred as the Vietnamese government attempts to crackdown on illegal bear bile farms. Today, only 1,245 of the animals remain in captivity in bear farms across the country compared to nearly 2,000 in 2014 and more than 4,000 in 2005. Officials want all the remaining animals held in captivity in Vietnam to be sent to sanctuaries where they can see out their days free from torment. But the owners won't see a penny in compensation if the bears are taken away and are killing them to sell their body parts before they can be removed, it is claimed. In Halong Bay, an idyllic seaside resort in northern Vietnam popular with Brit holidaymakers, a staggering 30 out of 49 captive bears held there have died in the last three months. The government has ordered the remaining 19 bears at Halong Bay to be taken to Tam Dao national park 120 miles away, a sanctuary run by British charity Animals Asia by September. Officials are under growing international pressure to rescue the animals. A raft of celebrities such as Judi Dench, Stephen Fry and Ricky Gervais have signed a petition calling on Prime Minister Nguyen Tan Dung to save the remaining bears in Halong Bay. Skyfall star Dame Judi, 80, blasted: 'These moon bears have been used and abused by the cruel bile industry and are now being left to die. 'We are asking the Vietnam government to step in and enable Animals Asia to rescue these beautiful animals. They deserve their sanctuary.' In one  farm in Halong Bay, Cau Trang, 22 bears from just 27 in total have died since November. Four bears were reported to have died there in one day – raising suspicions the animals were killed to order. MailOnline dodged security guards to get into Cau Trang and witness the disgusting conditions the remaining five bears are forced to live. Packed into rusty metal cages, one of the bears lay motionless on the ground, seemingly giving up hope of ever being rescued. Another rocked manically from side to side and a third had a gushing head wound. A patch of dry ground 20 metres away from the cages was coated with clumps of bear fur. Two teenage guards with a dog confronted our man before phoning owner Nguyen Trong Bo's son, Hung. When he arrived at the farm, Hung was asked where the other 22 bears had gone. He replied with a sarcastic smirk – claiming: 'They have been released into the forest.' He refused to answer further questions and ordered us to leave, shouting angrily: 'You have no right to interfere in our business … If you take my picture I will sue you.' Butchered: Vietnam's moon bears are killed are sold for £625 each and smuggled to China for use in traditional medicine. Their paws, meat and gall bladders are used by men to increase sexual potency and cure hangovers . Death sentence: bears are being slaughtered and sold for their body parts to the lucrative trade in Chinese medicine . Cruel: 30 bears have died at illegal bile farms in the tourist resort of Halong Bay in the past three months. When contacted, one farm owner claimed his had all died from disease and old age. Bear bile farming was banned in Vietnam in 1992 . Bear owners are killing the animals to 'extract the last ounce of blood' out of them before officials force farmers to hand over the animals to wildlife sanctuaries. Greedy owners are demanding compensation from the government . Earlier his father Nguyen responded to a Vietnamese journalist, and claimed the four bears which died in one day at his farm were all aged over 20 and had been 'eating less' in recent months. Because of their endangered status – less than 100 moon bears remain in the wild in Vietnam – the death of any bear should be reported to local officials who are meant to oversee its post mortem and burial. But the sources told MailOnline official procedures are routinely bypassed and dead bears disposed of quickly by farmers on the pretext that the animals might have died from infectious diseases. Requests by animal welfare groups to inspect the bears are rebuffed and inquiries about burial sites brushed aside with explanations that bears might have been dug up by thieves, the sources said. The Prime Minister's office has instructed local officials and government departments to arrange the transfer of Halong Bay's surviving bears to the Animals Asia sanctuary. However, aid workers from Animals Asia say the process is being held up by greedy farmers' demands for compensation, and warns the remaining bears could be dead soon unless action is taken quickly. The charity's Vietnam director Tuan Bendixsen told MailOnline: 'We have received unconfirmed reports that bears are being deliberately killed and their body parts sold on the black market as bear farmers look for ways to recoup as much money as they can from the bears. 'Farmers are supposed to be caretakers of these animals. Selling a bear dead or alive is a criminal offence, as is failing to provide a proper level of care.' The charity founder, British nurse Jill Robinson MBE, who has saved countless bears from the cramped cages where they are kept, added: 'We are sickened to think that bears at death's door are possibly being slaughtered and exploited in such a mercenary way. As for the bears who have already died, who conducted post mortems? Who has disposed of the bodies and where are they? 'We, and thousands of supporters across the world, are heartbroken and frustrated that these slowly dying bears are not given the dignity of rescue and where necessary peaceful euthanasia after all they've suffered on the farms. 'For pity's sake, we implore the Prime Minister to release them from their pain, confiscate them in to our sanctuary, and allow our team to give them the love and care they deserve.' MailOnline man Simon Parry at the gates of Cau Trang bear farm in Halong Bay where 22 bears have died since November. Four died at the farm in a single day. Only five bears are left at Cau Trang . Bear bile farming involves crude catheters jabbed repeatedly into the caged bear's abdomen and gall bladder to drain out the fluid. This painful process takes place twice a day. The digestive juice contains Urso Deoxycholicacid (UCDA), a prized ingredient in traditional Chinese medicine, an industry which is worth £1.5 billion. It can aid the treatment of liver and heart disease and reduce swelling when mixed with alcohol and rubbed on bruises. Men in China have also used bear bile as an aphrodisiac or to help cure hangovers. More recently it has been added to non-medicinal products such as wine and shampoo in China, the WSPA claims. Bile farming has been banned in Vietnam since 1992. In 2005 4,239 captive bears were micro chipped and farmers were told they could keep them but could not extract bile from them. But the cruel and illegal practice remains widespread. Until recently Korean, Japanese and Taiwanese tourists regularly visited bear farms in Halong Bay where they would buy bile and insist on watching it being extracted from bears to ensure it was genuine and fresh. Details of the campaign to save the remaining captive Halong Bay bears are available at http://halong.animalsasia.org/savehalongbears .
Two moon bears on Vietnamese bile farms are brutally slaughtered a day . Bears are kept in tiny 2ft by 4ft metal 'crush cages' with no room to move . Their body parts are sold on the black market for just £625 per bear . MailOnline probes resort where 30 bears have been killed in three months . Dame Judi Dench signs petition calling for end to cruel bear bile trade .