The police have arrested a man over the brutal killing of three orang-utans at a nature reserve in Sabah, local media reported Tuesday.

He was identified as a disgruntled former worker at the reserve.

The orang-utans, named Mambo, Terry and Marrie, were found speared to death at the Shangri-La Rasa Ria Resort a week ago.

Another two of the endangered red-haired apes - Tiger and Sherry - were wounded and are undergoing treatment at the Sepilok orang-utan sanctuary in Sabah.

Rewards on offer

All five primates had been captured on Sabah's east coast where their forest habitat has been gradually shrinking, making way for plantations.

Rewards totalling RM60,000 were offered for information leading to the arrest of those behind the killings.

A primatologist has warned that the orang-utan population would disappear in the next 20 years if the persistent decline continued.

Borneo and the Indonesian island of Sumatra had lost 91 percent of their orang-utan populations over the past 100 years, Kinabatangan Orang-utan Conservation Project director Marc Ancrenaz was quoted as saying by The Star .

Severely threatened by habitat loss, poaching and forest fires, the species would disappear unless conservation measures were taken immediately.

There are an estimated 13,000 orang-utan remaining in Sabah, making it the last stronghold for the primate in Malaysia, he said. - AFP