The Amazon rainforest has won a temporary reprieve from an invasion by soya farmers, after Brazil's major traders in the bean agreed to a two-year moratorium on crops from newly deforested land.

In recent years soya has overtaken illegal logging and ranching as the main engine of deforestation in the biggest and most important rainforest on the planet.

John Sauven, a campaign director at Greenpeace, said: "This is an important step as this is the first time we've had the multinationals and the Brazilians sit down and talk about environmental issues. But it will only prove to be a major breakthrough if real action is taken on the ground."

Soya has established itself as a profitable link in the processed food chain and Brazil has emerged as Europe's main supplier of soy, most of which is fed to livestock, helping to deliver cheaper meat products to supermarket shelves and fast-food counters.

The deal follows a three-year investigation by Greenpeace into the impact of the soy trade in the Amazon. Multinationals, such as Cargill, the largest privately owned company in the world, have set up soy operations inside the fragile Amazon biome.

Working with local campaigners, such as Fr Edilberto Sena, the Catholic priest who has received death threats for his part in publicising the illegal activities of the soya farmers, such as slashing and hacking their way into protected forests and indigenous lands. "They see the soya as a commodity, but we see it as the death of the forest," said Fr Edilberto.

In the area of Santarem, in Para State, the opening of Cargill's soya port has coincided with a five-fold increase in deforestation. "It's no longer unseen, it's no longer hidden.

"The companies know they're being watched. The government can't claim they don't know what's going on," said Mr Sauven.

Pressure has been mounting on the soya traders following a Greenpeace report earlier this year and an international conference in the Amazon, led by the head of the Eastern Orthodox Church, took scientists, politicians and religious leaders to the frontline of the soya wars in Santarem last week. The Religion, Science and the Environment symposium ( www.rsesymposia.org ) coincided with talks in Sao Paolo this week between soya traders and major UK food companies, which finally delivered a deal to halt the destruction.

In a joint statement, issued yesterday, the Brazilian grain exporters' association, which includes all the major multinationals, committed itself to "seeking to reconcile environmental conservation with economic development, through responsible and sustainable use of Brazil's natural resources". The Brazilian rainforest is the world's biggest carbon sink and a vital defence against the escalating problem of climate change.

The Amazon basin contains half of the world's remaining rainforest and is the most concentrated area of biodiversity on the planet, with as many as 300 tree species per hectare. Previous threats to the Amazon from illegal loggers and cattle farmers have converted the forest into agricultural land at a rate equivalent to five football pitches every day. But soya farming is even more pernicious, turning the thin top soil of the region into desert in as little as three years, thanks to intensive farming efforts.

The efforts of agro-business giants such as ADM, Amaggi group and French-owned Dreyfus, to open up the Amazon to the soy trade has seen illegal land grabbing on a massive scale by farmers keen to cash in on lucrative soy contracts. The protein-rich soybean in turn gets shipped to Europe where it makes up an increasing proportion of the feed given to chickens, pigs and cows.

The industry, under pressure from customers such as McDonald's, has now agreed to work with government agencies and NGOs to set up a monitoring system and safeguards to ensure that soya is not sourced from newly deforested land. "This is a critical first step but there is much more to be done," said Lori Johnson, a vice-president at Cargill.

Fundamental differences remain between conservationists and companies such as Cargill over whether there should be a future for soya farming in the Amazon basin. Cargill insists that it is a vital part of development for the 20 million people living in the area, who are among Brazil's poorest people.

How 'Independent' played key role in industry U-turn

The scale of the destruction of the Amazon rainforest and its replacement with a vast monoculture of soybean plantations was revealed by The Independent in May last year.

The millionaire farmer and ambitious state governor of Mato Grosso, Blairo Maggi, was identified as the man most responsible for the "ruthless obliteration" of an area commonly acknowledged as the lungs of the world.

Mr Maggi, whose company is the largest soybean producer in the world, said he felt "not the slightest guilt" over deforestation. The Independent's front page was reproduced across the Brazilian media, to the acute embarrassment of a man widely tipped to be planning a bid for the presidency in Brazil.

The country has made agriculture its biggest export earner and soya has emerged as its principal commodity. The soy boom was fed by concerns over cattle feed in the wake of the BSE crisis and European demand for soy-based cattle feed is soaring.

Last week, The Independent visited the front line of the soya wars where illegal farms are cutting deep into supposedly protected forest. Local communities, NGOs and conservationists complain that the insatiable hunger for soy was destroying the forest. A vast port facility built by the US multinational Cargill has replaced the fishermen's beach in Santarem. The port has twice been ruled illegal by Brazilian judges but Cargill has appealed to the High Court to be allowed to continue this lucrative trade.

Daniel Howden