Brazilian authorities say about 1,000 people gathered in South America's biggest city to protest against environmental law changes that they say would increase deforestation in the Amazon.

Brazil's Congress is expected to vote this week on whether to ease environmental laws in favor of Brazilian farmers who are seeking more space to raise cattle.

Farmers are supporting a bill that would let them clear half the land on their properties in environmentally sensitive areas. Current law allows farmers to clear just 20 percent of their land in the Amazon zone.

The protesters want revisions in the legislation to protect the rain forest.

Former Brazil Environmental Minister Marina Silva attended Sunday's protest in Sao Paulo.