"The clearings are large enough to be seen from satellite," said Paulo Adario, coordinator of Greenpeace's Amazon campaign.

The Amazon, most of which is located in Brazil, is larger than all of Western Europe combined and shelters up to 50 percent of the world's animal and plant life. Environmentalists fear it is being destroyed at an unsustainable rate and last year deforestation was the highest in five years.

Logging of mahogany, which can fetch $1,600 per 10.76 square feet (1 square meter) on international markets, was banned in Brazil in 1996 on worries it is becoming extinct. Logging of any kind is outlawed on Indian land.

There are 13 permits allowing logging of mahogany, however, that include requirements for sustainable replanting of trees by logging firms.

But of the companies that hold permits for sustainable mahogany logging, five have been fined for illegal logging. "We suspect that some of these permit holders are the ones logging in the Indian area," said Adario.

An official at the Brazilian government's environmental agency Ibama said the clearings on the kayapo land were as large as (492 feet by 492 feet) (150 metres by 150 metres).

A recent study by the World Wildlife Fund found that 4.23 million cubic feet (120,000 cubic metres) of mahogany from Latin America reaches global markets every year, mainly from Brazil, Bolivia and Peru. A large portion of that is illegally logged.

It is not uncommon for Brazilian indians to allow loggers onto their land, even though it is illegal, to make some meager earnings.

Adario said ending the logging on their land would require finding ways to help the Indians.