A key population of orangutans in Sabah is under threat of extinction as their habitats are destroyed mainly to make way for palm oil plantations, scientists and officials said today.

The conclusion comes after a study of orangutans and other animals along the Kinabatangan river in Sabah, where chunks of forest have been carved away by private land ownership, mainly plantations.

Findings show Kinabatangan orangutans could face extinction in less than 50 years if immediate measures are not taken to restore habitats, the scientists and officials said.

Sabah Wildlife Department director Patrick Andau said orangutans were often alienated as they were confined to small areas between patches of forests and private land.

"The species are at the risk of becoming extinct because of the fragmentation of their habitats," he told AFP .

"This is simply because the land has been alienated where parts of it are owned by the private sectors ... a majority of which are plam oil plantation owners."

Orangutans are Asia's only great ape and are split into two species, one of which, the Pongo pygmaeus, is found only on Borneo, an island shared by Indonesia, Malaysia and Brunei. Most of them are in Malaysia's Sabah province.

Forest corridors

Although a wildlife sanctuary has been built in the 45,000-hectare Kinabatangan area, plantations can still be built outside it, further isolating orangutan populations, scientists said.

"Habitat fragmentation increases as they are still trying to expand palm oil plantations outside protected areas," conservation geneticist at Cardiff University, Benoit Goossens, told AFP .

In the study, scientists created a model for the future survival of orangutans which analyzed 11 isolated populations in lower Kinabatangan, where 1,000 of the estimated 11,000 orang-utans in Sabah live.

"The model shows that if nothing is done, most of these sub-populations will be extinct in the short and medium terms (less than 50 years)," Goossens said in a statement on Sunday.

Researcher Isabelle Lackman-Ancrenaz from the Kinabatangan Orangutan Conservation Project said the sub-populations could be saved by creating "forest corridors" to allow orangutans to travel between forest areas.

"However, establishing corridors is a slow process and extinction may still occur in the meantime," she warned in the statement.

Besides forest clearing, orangutans are also threatened by forest fires, commercial logging, hunting and poaching for the meat and pet trades.