In its report called "Treasure island at risk", the World Wide Fund (WWF) said the loss of forest would drastically affect the island's wildlife, endangering ecological wonders like the pygmy elephant and orang-utan, whose long-term survival is already in doubt.

"The consequences of this scale of deforestation will not only result in a major loss of species but also disrupt water supplies and reduce future economic opportunities such as tourism and subsistence for local communities," Chris Elliott, director of the WWF's Global Forest Programme, said in a statement.

By 2020, the remaining populations of orang-utans may be too small to be genetically viable due to fragmentation of their habitat, the WWF report said.

Indonesia, having lost more than 70 percent of its original frontier forest, has launched a crackdown on illegal logging, but many activists complain the authorities have failed to catch the big bosses behind the lucrative trade.

Indonesia shares jurisdiction of Borneo, which lies at the centre of Indonesia's archipelago, with Malaysia and Brunei.

The WWF wants to help the three nations to convert more than 22 million hectares of rainforest in an area known as "Heart of Borneo" into a reserve taking up a quarter of the island.

"In the Heart of Borneo we can still achieve conservation on a big scale and win before we are left with small, fragmented forest patches," said Stuart Chapman, international coordinator of the Heart of Borneo Initiative.