They warn that rain forests in countries such as Indonesia and Brazil could disappear within 20 years.

Illegal logging is a particular problem in Indonesia, according to Marco Tacconi, an economist at the Centre for International Forestry Research.

Indonesian rainforests

Indonesia has about 10% of the world's remaining tropical forests - second only to Brazil Forest cover fell from 162m ha (400,300,000 acres) in 1950 to 98m ha (242,200,000 acres) in 2000 Nearly 2m ha (4,942,000 acres) are now being destroyed every year Sources: World Resources Institute, Global Forest Watch, Indonesia

He blamed illegal logging primarily not on poverty, but corruption.

It is estimated that two-thirds of all logging in Indonesia is illegal.

Mr Tacconi maintained that people who lived in the forests did not have the financial resources to carryout such an activity.

Laws flouted

There are laws against illegal logging but they have little impact.

While the government has introduced curbs on exports, these are believed to have had little effect because much of the timber illegally collected is used domestically.

Mr Tacconi has never heard of anyone being jailed following the prosecution of people caught transporting or exporting logs.

"Everybody knows that the law enforcement is very weak," he said.

The Indonesian government's senior economic policy adviser, Mahendra Singer, admitted the legal process to prosecute the illegal loggers needed to improve.

"I'm not trying to give an excuse," he told the BBC's World Business Report.

"We have to understand the experience as well as the constraints and limitations that the present legal system can do."

He admitted that the government was only just beginning to pass laws which deterred illegal logging.