IT IS the '11th hour' for many primates as nearly two thirds are threatened with extinction, scientists have warned.

Escalating pressure from human activities such as cutting down forests, expanding agriculture and building dams and roads are putting apes, monkeys and other primates at risk of dying out, researchers writing in the journal Science Advances said.

Experts from Oxford Brookes University have warned without immediate action to protect them, human's closest relatives face mass extinctions in the next 25 to 50 years.

Professor Anna Nekaris, professor in anthropology at Oxford Brookes University and one of the report's authors said: "The impending extinction of our closest relatives should not be taken lightly.

"Primates, be they large and charismatic or small and nocturnal, are vital parts of the ecosystem."

Aside from humans, there are 504 recognised species of primates, from the tiny Madame Berthe's mouse lemur which weighs just 30g (1oz) to the 200kg (31st) male western and eastern gorillas.

Around 60% are under threat of extinction and 75% are seeing declines in numbers.

The researchers added: "Considering the large number of species currently threatened and experiencing population declines, the world will soon be facing a major extinction event if effective action is not implemented immediately."

The latest assessment finds 87% of species in Madagascar are threatened, as are 73% in Asia, 37% in mainland Africa, and 36% in the Americas.

University of Illinois anthropology professor Paul Garber, who co-led the study, said: "This truly is the 11th hour for many of these creatures.

"Several species of lemurs, monkeys and apes - such as the ring-tailed lemur, Udzunga red colobus monkey, Yunnan snub-nosed monkey, white-headed langur and Grauer's gorilla - are down to a population of a few thousand individuals.

"In the case of the Hainan gibbon, a species of ape in China, there are fewer than 30 animals left."