ASUNCIÓN, Paraguay, June 5 (UPI) -- Brazil's environmental authority has approved one of the final requirements for state-run oil company Petrobras to proceed with oil exploration at the mouth of the Amazon River.

After several rejections, Petrobras secured approval from the Brazilian Institute of Environment and Renewable Natural Resources for its wildlife protection plan. The decision allows the company to proceed to a preoperational evaluation phase.

This stage includes live emergency simulations to test Petrobras' response capabilities. The success of these tests will be key to the environmental authority's final decision whether to issue a drilling license.

Petrobras aims to drill a well about 109 miles off the coast of Amapá state, in a maritime zone known as Block 59. The company says the activity will be low-impact and time-limited. Still, the project has sparked widespread environmental and social concerns.

Environmental groups and experts have warned about the risks to the mouth of the Amazon River, an ecologically rich region and home to coral reefs, mangroves and endangered species.