The endangered list includes the Western Hoolock gibbon (Hoolock hoolock) found in India, Bangladesh and Myanmar.
One species of monkey that has not been seen for many years is already thought to have died out.
A detailed assessment of the 394 species of primates from South America to Indonesia has found that 29 per cent are in danger of disappearing due to hunting, habitat loss and climate change. Some are already on the brink of extinction, it said.
One species, Miss Waldron's red colobus, of the Ivory Coast and Ghana, is now feared to have become extinct while the golden-headed langur, of Vietnam, and China's Hainan gibbon are numbered only in their dozens.
The Horton Plains slender loris, of Sri Lanka, has been sighted just four times since 1937 and the Sumatran orangutan, of Indonesia, is suffering one of the fastest rates of decline of all primates as a result of being forced out of its rainforest habitat by human encroachment.
A report by The World Conservation Union (IUCN), which draws up the official ''red list'' of endangered species, has identified the 25 most endangered primates on the planet.
''You could fit all the surviving members of these 25 species in a single football stadium. That's how few of them remain on Earth today,'' Russell Mittermeier, president of Conservational International, the Washington-based environmental group, was quoted by the Independent as saying.
''The situation is worst in Asia, where tropical forest destruction and the hunting and trading of monkeys puts many species at terrible risk. Even newly discovered species are severely threatened from loss of habitat and could soon disappear,'' he said.
A separate report by the UN Environment Programme on the state of the world highlighted the bushmeat trade as a particular danger to apes and monkeys. The trade, it said, is running at six times the level that is considered sustainable.
Overall 114 of the 394 species of apes and monkeys are classified as threatened with extinction, the IUCN said.
Madagascar and Vietnam each have four primates on the new list, while Indonesia has three, followed by Sri Lanka, Tanzania, Ivory Coast, Ghana and Colombia with two each, and one each from China, Cameroon, Equatorial Guinea, Kenya, Nigeria, Burma, Bangladesh, India, Peru, Venezuela and Ecuador.
Dr Mittermeier called for protecting the forest cover and efforts to diminish effects of cliamte change.
''By protecting the world's remaining tropical forests, we save primates and other endangered species, while preventing more carbon dioxide from entering the atmosphere to warm the climate,'' he said.
The list of the most endangered species includes 11 from Asia, seven from Africa, four from Madagascar and three from South America. The loss of primates is also affecting the health of trees because of the role they play in seed dispersal and forest regeneration, the report said.