The impending disaster, which affects species in three continents, would result in the first primate extinctions in more than a century and could have serious implications for ecosystems throughout the world.

The report, which was compiled by more than 50 experts from 16 countries, lists the world’s 25 most endangered primates. These include the golden-headed langur, of Vietnam, and the Hainan gibbon, of China, both of which number only in the dozens. Also at risk are several lemurs from Madagascar, such as the greater bamboo and white- collared species.

The study says that 25 per cent of 625 species are likely to disappear from the planet in as little as 20 years unless action is taken.

The illegal animal trade is named as the primary factor in the declining number of primates, together with increased hunting of meat for commercial purposes and for use in traditional medicine. Also to blame is the clearing of forests for agricultural purposes and for the supply of fuel wood.

The list of 25 primates contains species from South America, Africa, Asia and Madagascar, indicating that threats to monkeys, lemurs, great apes and other non- human primates are widespread and exist wherever they live.

In Asia 50 per cent of native primates are under threat. Countries such as China, India and Vietnam contain a disproportionate number of endangered primates because of the near-total destruction of their original forests. Another problem there is the live capture of animals, which are sold as pets.

In Madagascar, which contains several rare primates not found elsewhere, the situation is even more severe, with 60 per cent of species said to be at risk. Several of these, such as Perrier’s sifaka, are restricted to small patches of tropical forest, which has left them vulnerable to threat.

Russell Mittermeier, president of Conservation International, which co-wrote the report, said: “More and more, mankind’s closest living relatives are being cornered into shrinking areas of tropical forest. This is especially true of Madagascar, one of the planet’s biodiversity hotspots that has lost most of its original forest cover. More than half its lemurs, none found anywhere else in the world, are threatened with extinction.

Although some species on the list still total in their thousands, the rate at which they are disappearing has caused concern for conservationists.

The Sumatran orang-utan, which numbers a few thousand, has been particularly affected due to the tsunamis that devastated the Sumatran coast in December. The report said that the Boxing Day earthquake off the Indonesian coast and the waves that it triggered had started a possible new threat to orang-utan habitat from the resettlement of the thousands of people made homeless.

Other species at risk of extinction are the Tana River red colobus, from Kenya, and the Bioko red colobus, in Equatorial Guinea, both of which may well be gone within the next 20 years.

Mr Mittermeier said that the rapid decline of primates could have grave consequences beyond conservation concerns. “If you look at why people go to Madagascar, for example, it is primarily to see the many types of lemurs that exist there. If they disappear, so will much of the eco-tourism that the country needs.”

He also pointed out the implications for the environment. “By dispersing seeds and interacting with their surroundings, primates support much of the plant and animal life that make up the earth’s forests,” he said. “We were so pleased that we hadn’t lost one species of primate in the 20th century, given that every other major mammal group has suffered losses — but now, unless we take action, it’s looking quite possible that the same could happen to primates.”

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