London: A new species of great ape has been discovered by British scientists and immediately listed as the most endangered in the world.

Conservationists had known for several decades that a curious population of orang-utans lived in the Batang Toru forests of North Sumatra, Indonesia, but until recently had been unable to compare them with other apes.

New species: A Tapanuli orang-utan with its baby in Batang Toru Ecosystem in Tapanuli, North Sumatra. Credit:James Askew/Sumatran Orangutan Conservation Programme via AP

However, after discovering the body of an ape, experts at Cardiff University were able to study its features and DNA to determine its species.

To their surprise, they discovered it was entirely new, and named it Pongo tapanuliensis, or the Tapanuli orang-utan - the first new ape species discovered this century.