BARCARENA, Brazil (Reuters) - A Brazilian government-backed institute is readying new evidence of contamination near the world’s biggest alumina refiner, Norsk Hydro ASA’s Alunorte, in the northern state of Para, a researcher told Reuters.

Slideshow ( 4 images )

A more complete report being prepared for release next week should reveal that there was a waste leak at the plant, said Marcelo Lima, a public health researcher at the Evandro Chagas Institute, a research facility linked to the Ministry of Health.

“It will tell more of the story, with new evidence,” Lima said on Thursday.

Flooding at the Alunorte plant last month sparked fears of a leak of toxic bauxite waste around the facility and government warnings of contamination.

A Feb. 16 thunderstorm dropped 200 millimeters (8 inches) of rain in 12 hours, causing red-colored water to flood streets, homes and areas of Amazon rain forest near the plant.

Authorities ordered the plant, in Bacarena city, to cut output in half until it addressed government concerns, leading Norway-based Hydro to declare force majeure with no time set to restart the plant.

Hydro has so far denied any negative environmental impact.

The company said in a statement on Friday that it had received a report from federal watchdog Ibama mentioning a lateral leak. It said the leak was contained and there was no contact with the environment.

The company and government continue to present divergent accounts of what happened.

Five officials at the Alunorte facility, who asked not to be named because of company policy, said the incident began with a lightning strike leading to a power failure.

Pumps shut down as the storm, flooding the administrative area of the plant that did not contain hazardous bauxite waste, according to the officials.

A small amount of untreated water from the area leaked out of cracks in a sealed, out-of-operation drainage tube and reached the nearby forest, they said.

At a separate refinery area, which includes two large waste deposits from processing bauxite, pump units connected to waste treatment areas suffered shutdowns but were quickly reconnected, the officials said.

But according to Lima, a separate duct leak, to be detailed in the new report, would have carried waste from bauxite processing at the company’s oldest waste deposit.

The institute has also collected samples showing the presence of harmful materials in soil and water, including lead, which could indicate that bauxite leaked as well, he said.