Brasilia, Brazil ? Environmentalists were caught off guard when South American leaders announced plans to build a massive natural gas pipeline through the Amazon rain forest.

Proponents say the $20 billion project, still in early planning stages, will help satisfy the growing regional demand for gas and help make South America less dependent on outside sources.

But environmentalists say it could damage part of the Amazon – the world’s largest wilderness – by polluting waterways, destroying trees and creating roads that could draw ranchers and loggers.

Venezuelan President Hugo Chavez says the pipeline is a central part of his efforts to reduce dependence on the United States and its pressure for free market policies known as the Washington Consensus.

At a meeting in Brazil’s capital earlier this month, the presidents of Venezuela, Argentina and Brazil promised to come up with the first set of preliminary studies for the 5,000-mile pipeline, stretching from Venezuela to Argentina.