By Richard Black
Environment Correspondent, BBC News website
In the dense central forests of Borneo, a conservation group has found what appears to be a new species of mammal.
WWF caught two images of the animal, which is bigger than a domestic cat, dark red, and has a long muscular tail.
Local people, the WWF says, had not seen the species before, and researchers say it looks to be new.
The WWF says there is an urgent need to conserve forests in south-east Asia which are under pressure from logging and the palm oil trade.
The creature, believed to be carnivorous, was spotted in the Kayan Mentarang National Park, which lies in Indonesian territory on Borneo.
The team which discovered it, led by biologist Stephan Wulffraat, is publishing full details in a new book on Borneo and its wildlife.
"You don't find new mammals that often, and to do so must be extraordinary," said Callum Rankine, head of the species programme at WWF-UK.
"We've got camera traps there, which are passive devices relying on infra-red beams across forest paths," he told the BBC News website.
"Lots of animals come past - it's much easier than pushing through the forest itself - and when an animal cuts the beam, two cameras catch images from the front and back."
Not a lemur
So far, two images are all that exist. But they were enough to convince Nick Isaac from the Institute of Zoology in London that the animal may indeed be new.
The find was made in Kayan Mentarang national park on Borneo
"The photos look most like a lemur," he told the BBC News website. "But there certainly shouldn't be lemurs in Borneo."
These long-tailed primates are confined to the island of Madagascar.
"It's more likely to be a viverrid - that's the family which includes the mongoose and civets - which is a very poorly known group," Dr Isaac said.
"One of the photos clearly shows the length of the tail and how muscly it is; civets use their tails to balance in trees, so this new animal may spend chunks of its time up trees too."
That could be one reason why it has not been spotted before. Another could be that access to the heart of Borneo is becoming easier as population centres expand and roads are built.
The WWF says this is the heart of the issue. It accuses the governments of Indonesia and Malaysia, which each own parts of Borneo, of encouraging the loss of native jungle by allowing the development of giant palm oil plantations.
Last week Pehin Sri Haji Abdul Taib Mahmud, chief minister of Sarawak, the larger Malaysian state on Borneo, said that such claims are unfounded and part of a smear campaign.
He told the BBC News website that palm oil plantations are mainly sited on land which had previously been cleared for cultivation or are in "secondary jungle".
But the WWF says species like the new viverrid - if new viverrid it be - are threatened by such development.
It is concerned that other as yet unknown creatures may go extinct before their existence can be documented.
The group is planning to capture the new species in a live trap so it can be properly studied and described.