However, the country's environment ministry says any new permits for felling trees will be subject to strict guidelines.

Some conservationists, who doubt whether any new controls can be effectively enforced, have questioned the wisdom of issuing permits.

Brazil's authorities refused to issue new logging permits in February after they discovered more than 15,500 square kilometres (6,000 square miles) - an area the size of Belgium - was cleared in 1998.

This was a rise of nearly a third on the previous year's clearing rates.

New commitment

The new guidelines limit local farmers to clearing just three hectares a year. Logging firms signing up to the agreement have also pledged to make better use of areas which have been partially logged, and to limit their use of fire in clearing forest.

Antonio Prado, a spokesman for IBAMA - Brazil's environment protection agency - says the agreement marks the first time such a commitment has been reached between government, loggers and environmental groups.

"I think it was a good step," he told the BBC. "The agreement with the loggers is an intial one. The most difficult part will come now, I would say, to change a simple and predatory logging activity into one that is a sustainable. This is the difficult task."

Mr Prado said convincing Brazilian loggers to accept sustainable practices will also require financial incentives, and he said will be seeking economic support from Western countries to help IBAMA enforce its new rainforest guidelines.

Effective enforcement

The environmental campaign group, Friends of the Earth, says the agreement is a welcome step. But its spokesman Tony Juniper believes IBAMA will have to overcome a history of failing to enforce conservation laws if the rainforest agreement is to succeed.

"The ban that preceded this agreement wasn't working," he says.

Whether this will or not is a different question, but I guess at the end of the day we have to look at the lead agencies in the Brazilian government - Brazil's environmental enforcement instution in the form of IBAMA - to see if they really are up to the job in terms of the resources they have available and the commitment of their staff to do it."

If the new measures succeed, they could make a significant difference in preserving one of the world's most important natural resources.

New research

Research just published shows the true extent of rainforest damage in the Amazon is more than twice as great as present estimates suggest.

In the study, scientists compared satellite data with surveys of what was actually happening on the ground. They found the remote sensing data from orbiting spacecraft did not give a true picture of what was really going on in the Amazon.

The researchers interviewed 1,393 wood mill operators, representing more than half the mills in 75 Amazonian logging centres.

They also interviewed 202 landlords, whose properties covered 9,200 sq km.