Brazil's Amazon rainforest could be likened to America's Wild West of old, where he who had the biggest gun or fattest wallet wrote the rules. I travelled to the Amazon for Christian Aid in September to see whether measures agreed at the 1992 Earth Summit in Rio de Janeiro to protect the forests and its people from illegal loggers, goldminers and settlers are working.

Chief Tamakurale of the Parakana Indians, a tribe that lives beside a tributary of the Amazon in Para state, told me a typical tale: "We do not want the loggers on our lands. They give us diseases, they kill the forest animals and take turtles from the river so we have nothing to eat. They cut down the trees. If the trees go, some of our children may survive, but they will not be Parakana."

This may sound familiar. The Rio summit, which was attended by most world leaders, was supposed to signal a new willingness to take the environment and indigenous rights seriously. Though important conclusions were reached in Rio, much of the aid promised by developed countries at the summit to help developing countries preserve and sustainably use their natural resources has not been forthcoming. And it is ironic that in the rainforests of the host nation, Brazil, deforestation rates have increased from 11,130 square kilometres a year in 1991 just before the conference to 14,896 square kilometres a year in 1994.

In response to this alarming trend in deforestation, the Brazilian government itself launched new measures in the summer of 1996 intended to halt or slow this destruction. The government recognised that much of the problem is caused by mahogany logging in reserves like that of the Parakana, which are legally set aside for indigenous people. The mahogany loggers not only cause damage themselves but also open the routes by which other settlers follow, adding to the destruction.

Logging in indigenous areas is illegal but hard to trace because of the vast size of the Amazon, so Brazil set out its new measures in July to halt the illegal logging - a ban on new mahogany-felling licences and a re-evaluation of all existing licensees. Furthermore, the area within any logging concession that can be felled has been reduced from 50 per cent to 20 per cent.

Can these new steps have any impact? One of the biggest concerns is the Ibama (the Brazilian environment police). The Ibama is grossly underfunded: its budget was cut by 40 per cent in 1995 and now it has only 650 agents, 120 land vehicles and 30 boats to patrol an area the size of Western Europe.

Jose Lutzenberger, the former Brazilian secretary of state for the environment, summed it up when he said that Ibama outstations were "100 per cent branch offices of the logging companies". Given the large amounts of money to be made, corruption is rife.

We arrived in Para state during the burning season, one of the dry periods when huge areas of rainforest are burned and cleared for cattle ranching and farming. From our small propeller plane, the forest at first appeared like a green ocean, but soon smoke from forest fires enveloped the view in a grey-green haze.

We travelled to the reserve of the Kayapo Indians to locate trucks carrying illegal mahogany. To reach the reserve, we drove for two hours through the smouldering remains of what just days before had been pristine rainforest. Within minutes, we found a truck carrying about pounds 30,000 of illegal mahogany. The engine was still warm and a cabin door was open - the loggers had seen us coming and were probably watching from the undergrowth.

Instead of confiscating the vehicle and stolen wood as they are empowered to do, the men from Ibama punctured the tyres and took some photographs. They feared that guns were trained on us from the bushes. One officer muttered bitterly that to do their job properly, Ibama needed the resources to make more journeys like this, and more military back-up, so they would have less to fear from retaliation.

The Parakana know their land has been deforested illegally. We flew over a large deforested area that our GPS (global positioning service) proved was within the reserve.

A timber company called Perrachi was fined for illegally logging the area in 1993. Perrachi is one of the main suppliers of Brazilian mahogany to the UK market. While the UK's Timber Trade Federation claims that all Brazilian mahogany in the UK is now legally sourced, the Parakana claim that Perrachi is still handling timber from illegal logging within their reserve.

"The problem is that, to get around the law, timber companies work increasingly through sub-contractors. It is therefore hard to prove whether companies like Perrachi are involved," explains Tarcisio Feitosa of Cimi, an organisation supported by Christian Aid to work with Amerindian tribes.

"The government's new legislation, though a step in the right direction, cannot guarantee that mahogany on the market is legally and sustainably sourced. I would ask consumers in the UK to think twice before buying it," he said.

From the evidence I saw, the Brazilian government needs to do more. First, it must put more resources into ensuring that indigenous land rights are respected. Ibama also needs to be better managed and resourced.

Sarah Tyack of Friends of the Earth has a further request: "If the Brazilian government wants to prove its credibility on the environment, it should support a ban on the mahogany trade under Appendix 11 of the Convention on International Trade in Endangered Species, early in 1997." That would be a meaningful New Year's resolution.

The writer is a researcher for Christian Aid