BRASILIA, Brazil — Brazil will combat rising deforestation in the Amazon by sending extra federal police and environmental agents to areas where illegal clearing of the rain forest jumped dramatically last year, officials said yesterday. Authorities will also monitor the areas where the deforestation occurred in an attempt to prevent anyone from trying to plant crops or raise cattle there, Environment Minister Marina Silva said.

The measures were announced after President da Silva called an emergency meeting of Cabinet ministers because new data showed an apparent reverse of a three-year decline that Silva has repeatedly praised.

The clearing of Brazil’s Amazon rain forest jumped in the final months of 2007, spurred by high prices for corn, soy and cattle. The 36 areas being targeted registered the highest rates of deforestation, environmental officials said.

Officials will also try to fine people or businesses who buy anything produced on the deforested land, the environment minister said.

The plan means a 25% increase in the police force assigned to the region, though Justice Minister Tarso Genro did not say how many officers will take part.

Mr. Silva’s ministry announced Wednesday that as much as 2,700 square miles of rain forest was cleared from August through December, meaning that Brazil could lose 5,791 square miles of jungle by August of this year if the rate continues.

That would be a 34% increase from the 4,334 square miles that was cut down and burned from August 2006 through July of last year.

Although preliminary calculations can only prove that 1,287 square miles of rain forest were cleared from August through December, ministry executive secretary Joao Paulo Capobianco said officials are still analyzing satellite imagery and working under the assumption that the higher amount of jungle was cleared.