A new species of orangutan has been discovered in the remote jungles of Indonesia, immediately becoming the world's most endangered great ape, researchers said Friday.

"It's the first declaration of a new great ape species in about 100 years," Ian Singleton, co-author of the study and director of the Sumatran Orangutan Conservation Programme, told AFP.

The species, called 'Tapanuli orangutan', lives in the Batang Toru forest on Sumatra island, and numbers only about 800 in total, making it the most endangered great ape in the world, Singleton added.