By Andrew Harding BBC News, Borneo

Increasing global demand for palm oil is big business for those countries that can provide it, such as Indonesia's Borneo, but the introduction of plantations on a large scale could have a devastating effect on the island's rich wildlife.

Tanjung Puting sits on a peninsula that juts out into the Java Sea

So there we were, up a creek, in the dark, attempting to navigate by firefly. Not an exact science.

I once tried navigating by radiation, driving round a nuclear waste site in the Urals with a drunk guide and a Geiger counter - but that is another story.

This time, we were in a speedboat, in a jungle in Borneo.

Luckily for us, the fireflies had obviously done this sort of thing before.

They lit up the riverbanks like gaudy casinos, steering us away from the impenetrable, crocodile-infested undergrowth and out towards the sea.

As the river twisted, we held up our mobile phones which glowed like little beacons to guide the boats behind us.

We were leaving Tanjung Puting National Park on the southern coast of Borneo.

Plantation plan

Hundreds of orangutans will die as their habitat vanishes and the poachers and chainsaws move in

Somewhere behind the twinkling fireflies - presumably dozing by now - were several thousand orangutans, scattered around the forest canopy in their giant tree-top nests.

And somewhere beyond the orangutans, lined up in abrupt, orderly columns, like an army advancing on the park, were Borneo's vast palm oil plantations.

Elaeis Guineensis (palm oil) was the reason we had come to the world's third-biggest island.

The palm is an amazing plant: squat, spiky, and low-maintenance.

All you have to do is chop off the big clumps of orange-brown, conker-sized fruit, squeeze the oil out of them, and you have one of the most versatile products imaginable. One which, in theory, has impeccably green credentials.

Palm oil is already in one in 10 supermarket items, such as crisps, bread, and lipstick.

Soon it will be in our petrol tanks too, as bio-diesel, a renewable, green alternative to fossil fuels.

No wonder Indonesia is busy planting Elaeis Guineensis at breakneck speed.

It wants to triple the size of its plantations in 15 years, which is where things start to get messy.

Land distribution

Palm oil is the second-most widely produced edible oil after soybean

Stephen Brend is tiptoeing gently through the undergrowth, backing away from a grunting orange carpet the size of a jukebox.

The carpet's name is Kosasih, and he is a dominant male orangutan with boundary issues.

A few years ago the Hollywood star Julia Roberts got a fraction too close to Kosasih and was grabbed and locked in a rigid embrace.

Stephen is trying not to make the same mistake. He is a former royal marine, now working in Borneo as a conservationist for the Orangutan Foundation.

For years now, Stephen and his colleagues have been battling against local timber and palm oil companies, which are steadily encroaching on the national park where Kosasih lives.

They use satellite imagery and armed patrols to document and police the park.

But things have suddenly got a lot worse.

The Indonesian government has just announced that 30,000 hectares of the park are to be given over to logging and palm oil companies.

That is 15% of the park's forests.

Hundreds of orangutans will die as their habitat vanishes and the poachers and chainsaws move in.

Selling to China

Further inland, in an area known as the "heart of Borneo", much larger areas are being quietly handed over.

Ancient jungles are being carved up to make way for palm oil. So much for being environmentally friendly.

Last year a monstrous scam was uncovered.

The type of rainforests found in Borneo include rare peat swamp forests and heath forest

It involved creating the world's largest single plantation - the size of four million football fields - right in the middle of a rainforest that has survived many millions of years.

Much of the land chosen turned out to be unsuitable for plantations. It was too steep and too elevated. But that was never the point of the exercise.

The real plan was to chop down as much valuable hardwood as possible and sell it to China.

After all, why put plantations on Borneo's vast swathes of empty land when you can carve up the forests and make a fortune before you have even started? And, in the process, destroy one of the world's last great biological treasure houses.

The Indonesian government says it is now changing its plans to protect the rainforests and the indigenous communities living in them.

But environmental campaigners are sceptical.

Me too. This is a remote region, in a famously corrupt country, with fortunes at stake.

Kosasih grunts, picks up some bananas and wanders off into the undergrowth.

I look down at the ground to find one of his many girlfriends holding my ankle.

It is a gentle grip, but no amount of tugging will set me free.