London (PTI): Orangutans, the great apes known for their intelligence, could be the first endangered species to become extinct unless urgent action is taken to protect the animals from human encroachment, a new study has claimed.

Native to Malaysia and Indonesia in South East Asia, the orangutans are currently found only in the rainforests on the islands of Sumatra and Borneo. They're the only surviving species in the genus Pongo.

But, the study found that the orangutan population on Sumatra had fallen by 14 per cent, to 6,600 apes, while it had dropped by 10 per cent, to 49,600 apes on Borneo. In parts of Aceh province, no orangutans were found at all.

According to the researchers, the decline is due to illegal logging and the expansion of palm oil plantations in the two regions.

"It's disappointing that there are still declines, (despite) quite a lot of conservation efforts over the past 30 years," lead researcher Serge Wich of the Great Ape Trust in Iowa was quoted by 'The Independent' newspaper as saying.

The new study, the latest of many to predict the demise of orangutans, described the species' losses on Borneo as occurring at an "alarming rate", and said the situation on Sumatra was one of "rapid decline".

"Unless extraordinary efforts are made soon, (the orangutan) could become the first great ape species to go extinct," according to the study, published in the latest edition of the 'Oryx' journal.

In the study, the researchers recommended stronger law enforcement to help reduce the hunting of orangutans for food and trade.