Brazil announced the protection of a huge corridor of Amazonian rainforest today, in what environmental campaigners described as one of the greatest conservation achievements in recent years.

The world's largest tropical forest reserve will be created in Brazil's northern state of Para, where nine sections of rainforest will be protected, completing the country's commitment to the "Guyana shield", a plan to preserve an area that also touches on Guyana, Suriname and French Guiana.

Taken together, the Brazilian reserve will cover more than 130,000sq km, an area larger than England, according to the governor of Para, Simao Jatene, who announced the decision today.

The forest forms a significant part of the overall Guyana shield area of 400,000sq km, whose trees and rivers contain around 20 per cent of the world's freshwater.

"If any tropical rainforest on Earth remains intact a century from now, it will be this portion of northern Amazonia, due in large part to the governor's visionary achievement," said Russell Mittermeier, the president of Conservation International, a US-based environmental group that campaigned for the decision.

"The region has more undisturbed rainforest than anywhere else, and the new protected areas being created by Para state represent a historic step toward ensuring that they continue to conserve the region's rich biodiversity and maintain its essential ecosystem services," he said.

The jungle state of Para is at the heart of the world's battle to protect the Amazon rainforest. Last year, a 74-year-old American nun, Dorothy Stang, was murdered for her involvement in a campaign to halt illegal logging in the state.

Conservationists estimate that an area of rainforest larger than France has been destroyed in Brazil since 1970 and that Para represents one of the world's last "green lungs", capable of releasing massive amounts of oxygen into the atmosphere.

If not stopped, environmentalists have given warning that the current rate of logging and agricultural intrusion would destroy the rainforest entirely by 2050.

The protected area is home to some of the rarest species of rainforest life. Jaguars, giant anteaters, and black spider monkeys will benefit from the protection alongside endangered species such as the giant otter and northern bearded saki monkey.

"This is the greatest effort in history toward the creation of protected areas in tropical forests," said Adalberto Veríssimo, a senior researcher at Imazon, a Brazilian environmental group.

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