The logging is contributing to the destruction of the planet's greatest rainforest and threatening the survival of Indian tribes. These people are exposed to diseases which often prove fatal because they have no immunity. The hunting they rely on for food is disrupted by new roads, airstrips and encampments in the forest.
Britain is the largest importer of mahogany from Brazil. But the UK's Timber Trade Federation has no idea what proportion of the mahogany imported comes from illegal sources. Today it is meeting Brazilian government representatives in Brasilia in an attempt to find out.
Until now, UK timber firms have mainly relied on assurances from their Brazilian suppliers that the timber they buy has been legally extracted. But in a court case in Brasilia, three major suppliers to the UK were accused of taking large quantities of mahogany from three Indian reserves in the Amazon jungle state of Para.
A judge ruled, in granting a preliminary injunction, that three logging firms should close down their logging operations and airstrips and remove employees from three reserves covering 36,000 sq km (13,900 sq mls). He also ordered the Brazilian environment protection agency, IBAMA, and the agency that deals with Indians, FUNAI, to mount checkpoints on the main loggers' roads into the reserves.
Friends of the Earth in Britain has established that the companies, Parachi, Maginco and Impar, trade with several British mahogany importers. For instance, James Latham Ltd of Clapton, east London, takes mahogany from Perachi and Richard Burbidge Ltd of Oswestry, Shropshire, takes wood from Maginco.
A spokesman for Richard Burbidge denied its supplier had extracted timber illegally and said it was appealing against the injunction.
Tony Juniper, of Friends of the Earth, said: 'The evidence paints an increasingly disturbing picture of rainforest destruction. We don't need more propaganda - we need an import ban.' But the trade, and some independent experts, argue that a ban would only increase the rate of Amazon destruction. By shrinking demand it would lower the value of mahogany and the forests it stands in and give less incentive to conserve and replant.
Logging is only one of several causes of forest destruction, although it often 'starts the rot' that ends in total deforestation.
Juliana Santilly, a Brazilian lawyer for the Indian rights organisation that took the case to court, said yesterday: 'These Indians have had very little contact with outsiders.
'They live mainly from hunting and fishing; logging is threatening their way of life. Basically they are just being robbed.'
The federal government has often lacked the resources or willpower to defend Indian reserves against incursions by loggers, gold prospectors, ranchers and landless peasants. Sometimes Indians who have tried to keep out loggers have been killed.
In theory, all logging is tightly controlled, with timber firms having to demonstrate to IBAMA that they plant trees to replace all of those they fell or pay a replanting tax on lumber. In practice, there is weak enforcement and widespread corruption.
The most prized, expensive tree is mahogany which grows across much of the Amazon region. In 1991, Britain imported 45,762 cu m (more than 1.6 million cu ft) worth about pounds 22m, according to the Department of Trade and Industry.
Despite several years of campaigning for a ban on imports by Friends of the Earth and Green peace, British consumers continue to show a strong attachment to the dark, easily worked, hard wearing wood. However, one DIY chain, B & Q, recently said it would no longer stock Brazilian mahogany.
The Timber Trade Federation would like all of the imported timber to be harvested legally, but admits it cannot be sure that it is. 'This problem won't be solved tomorrow,' Geoff Elliott, of the federation, said.