Judge Carlos Eduardo Martins said he halted construction of the controversial Belo Monte dam because it would harm fishing by indigenous communities on the Xingu River in Para state.

The Belo Monte dam would be the world's third-largest hydroelectric energy producer, which straddles the border of Brazil and Paraguay.

The government has said the dam is necessary because it will be a source of clean, renewable energy, and help damage to the environment be minimized. But environmentalists and indigenous groups say the dam would devastate wildlife and the livelihoods of 40,000 people who live in the area to be flooded.

Celebrities including film director James Cameron are known to have joined activists in lobbying against the dam, increasing public?s interests towards the dam. When Cameron participated in protests against the project in Brazil last year, he compared the anti-dam struggle by indigenous people to the plot of his film "Avatar," which depicts natives of a planet fighting to protect their homeland from plans to extract its resources.