Brazilian power company MPX Energia announced Thursday it would appeal a Chilean court decision ordering a halt to a planned huge 2,350 megawatt thermal power plant on Chile's northern coast.

With a $4.4 billion investment, the coal and diesel-fired power plant would be the biggest in South America, but environmentalists say it would harm marine life in an area considered a wildlife reserve.

"MPX reiterates that the project fully complies with all environmental standards and it will appeal the ruling to the Supreme Court of Chile," said a statement from the company.

MPX is owned by billionaire Eike Batista.

The company's statement said an appeal would "demonstrate, through appropriate environmental and legal arguments, that the environmental license for Project Castilla meets all constitutional criteria."

It would be built, along with a coal terminal in nearby Punta Cachos, 800 kilometers (500 miles) north of the capital of Santiago in an area ecologists consider a wildlife reserve that includes penguins and sea turtles.

An appellate court decision Wednesday overruled a regulatory approval for the plant granted in February 2011 by Chile's Atacama Regional Environmental Commission. The court said there were "irregularities" in the approval process.

The ruling classified the power plant as an "annoyance" under standards of Chilean environmental law. As a result, the plant "is illegal and violates the right of appellants to live in a pollution-free environment," the ruling said.

MPX said Thursday the Castilla power plant would be "among the first thermal plants to be approved under the new rate of emissions standards (for carbon dioxide) recently established by the Chilean government, equivalent to the most demanding European standards."

The company said it plans to spend more than $1 billion on environmental protection around the plant, which would include two nature reserves covering 12,000 hectares.