A Chilean court on Thursday overturned a three-month suspension of a project to build a giant hydroelectric dam complex in the Patagonian wilderness, which environmentalists say will destroy a unique habitat.

Green campaigners plan to challenge an appeals court decision made in the southern port city of Puerto Montt in favor of the project, which aims to generate 2,750 megawatts of power.

The 2.9 billion dollar HidroAysen project, which belongs to Spanish-Chilean consortium Endesa-Colburn, has sparked huge and sometimes violent protests since a government commission approved it in May.

It involves building five dams in two river valleys in Patagonia, and the flooding of 6,000 hectares (15,000 acres) of pristine, largely uninhabited land in a quest to generate more electric power for Chile's booming economy.

Thursday's decision overturned a ruling in June to halt the project for three months to consider objections from opponents.

The government of President Sebastian Pinera argues the country needs the project -- which will increase Chile's power capacity by 20 percent -- to keep pace with energy demands and to head off looming shortages.

But those against say it will disfigure one of the last virgin territories on the planet, with forests and glaciers and lakes beloved by nature lovers the world over.

Prior to Thursday's ruling opponents said they would take their case to the Supreme Court or even the International Court of Human Rights if the decision went against them.

A lawyer for a consortium of opponents of the project, Marcelo Castillo, was quoted in Chilean media Thursday as saying he was confident in legal arguments that would be put before the Supreme Court.

The Pascua and Baker rivers, where the dams are planned to be built, are the largest in Chile, with crystaline waters fed by thousand-year old glaciers.

The project also includes construction of more than 2,000 kilometers (1,200 miles) of high-tension transmission lines and pylons that will carry electricity across nine regions of the South American country.

The project will need more than 5,000 workers who will be living in the remote area of Aysen for more than 10 years, effectively doubling the population of the region.