Brazil has agreed emergency measures to stem deforestation as government figures revealed a sharp increase in the rate of clearances in the Amazon.
Last year the president said his efforts were working
The steps were announced after an emergency cabinet meeting chaired by President Luiz Inacio Lula da Silva.
The measures include sending extra federal police and environmental agents to stop farmers and cattle ranchers illegally felling any more rainforest.
In the last five months of 2007, 3,235 sq km (1,250 sq miles) were lost.
Environment Minister Marina Silva said environmental agents and police would be deployed around 36 cities and towns where illegal clearing jumped dramatically last year.
People or businesses who buy anything produced on the deforested land could face fines, she said.
The plan involves a 25% rise in the police force assigned to the region.
The Amazon has long been known as the "lungs of the world"
The authorities will also monitor areas of deforestation, with the aim of stopping crop planting and cattle raising there.
Rising prices of raw materials and commodities could be spurring the rate of forest clearing, the environment minister said.
The state of Mato Grosso was the worst affected by the sharp rise in deforestation, contributing more than half the total area of forest stripped.
The states of Para and Rondonia were also badly hit.
Gilberto Camara, of satellite imaging institute INPE, said: "We've never before detected such a high deforestation rate at this time of year."
The environment ministry said the estimate for deforestation between August and December last year could more than double as detailed satellite images are analysed.
The total area affected could be as high as 7,000 sq km, it said.
The latest figures will be an embarrassment for the Brazilian president, says the BBC's Americas editor, Warren Bull.
Last year, President Lula said his government's efforts to control illegal logging and introduce better certification of land ownership had helped reduce forest clearance significantly.