Scientists say they have found the world's largest known population of an endangered monkey species in central Vietnam.

Surveys since 2005 by the World Wildlife Fund (WWF) and Conservation International have recorded at least 116 tree-dwelling, grey-shanked doucs, which are one of the world's 25 most endangered primates.

Scientists believe fewer than 1,000 such monkeys exist in five central provinces of Vietnam - Quang Nam, Kon Tum, Quang Ngai, Binh Dinh, and Gia Lai. They had previously seen only one other colony of more than 100 animals.

A Conservation International biologist says the finding, if put in a human perspective, is like discovering a new country with a billion residents.

A WWF expert says the discovery gives scientists a greater opportunity to overcome the threats facing the species and prevent its disappearance.

Some information for this report was provided by AFP, AP and Reuters.