Brazil's Senate has approved a controversial forestry bill that environmentalists say will deal a "mortal blow" to the already threatened Amazon region and open the door to even greater deforestation.

The bill, which will now go back to the lower house for review of some slight changes, was passed Tuesday by a vote of 58-8 as most members of the ruling coalition joined with a bloc of opposition legislators representing big landowners.

In approving the legislation, the senators ignored protests from environmentalists who have warned of the disastrous impact of overhauling the 1965 Forest Code.

The green light from the Senate ensures passage of the bill, which the lower house had approved in a first reading earlier this year by a vote of 410-63.

The bill, introduced by President Dilma Rousseff's administration and backed by the agribusiness lobby, proposes a reduction in the proportion of terrain private growers and ranchers must set aside as forest preserves from 80 percent to 50 percent.

It also states that a 15-meter (50-foot) swath of land must be protected on both banks of a river, down from 30 meters under the current code.

However, it also requires farmers to restore areas that have suffered environmental damage and provides economic incentives for rural producers that adopt sustainable practices.

The most controversial aspect of the legislation, however, is the amnesty it affords farmers who illegally expanded their farming and ranching operations through deforestation.

Rousseff was among the critics of the amnesty provision, saying that she may veto that and other sections of the bill.

Sen. Marinor Brito, of the leftist opposition Socialism and Freedom Party, said approval of the forest code overhaul marks "a dramatic turning point for Brazil and for current and future generations."

But Sen. Katia Abreu, a Brazilian Social Democracy Party lawmaker who also heads the National Agriculture and Livestock Confederation, came out strongly in favor of the legislation.

"Passage of this bill means doing away with the dictatorship of a half-dozen non-governmental organizations that controlled the Environment Ministry and makes clear that we all have a say in environmental matters," she said.

Greenpeace led the most recent protest against the bill Tuesday, saying in a rally outside the Senate building in Brasilia that it would erase all the gains Brazil has made in recent years in reducing Amazon deforestation.

Ten former Brazilian environment ministers also came together to oppose the bill, urging Rousseff in a letter a few months ago to impede a "disaster foretold."