More than 150 fishermen and indigenous people on Thursday began occupying one of four construction sites for Brazil's huge Belo Monte dam in the Amazon, the lawyer for a group fighting the project said.

Maira Irigaray, an attorney for the American non-governmental organization Amazon Watch said it was the most recent of several protests since June 2012.

Native people and settlers say they are still awaiting compensation promised by the Norte Energia, the consortium in charge of the construction work.

"Activities on the Pimental site, where the Xingu River already has dried up, are completely stopped and the 30,000 workers have been withdrawn by management at the request of the protesters," said Irigaray, who works with the "Xingu Vivo" movement that is spearheading opposition to the dam's construction.

Belo Monte, which is being built at a cost of $13 billion, is expected to flood an area of 500 square kilometers (200 square miles) along the Xingu River, displacing 16,000 people, according to the government.

Some NGOs have estimated that some 40,000 people would be displaced by the massive project.

The dam, expected to produce 11,000 megawatts of electricity, would be the third-biggest in the world, after China's Three Gorges facility and Brazil's Itaipu dam in the south.

A Xingu Vivo statement said the protesters were mostly fishermen from the village of Jericoa and members of the indigenous Xipaia, Kuruaia, Canela and Juruna peoples.

It added that fishing in Jericoa is no longer possible and there is no drinking water.

Protesters accuse Norte Energia of backtracking on accords signed in June when 150 indigenous people occupied the Pimental area for three weeks.

The native peoples want their lands demarcated and non-indigenous people removed from them. They also are demanding better health care and access to drinking water.

Indigenous groups say the dam will harm their way of life while environmentalists warn of deforestation, greenhouse gas emissions and irreparable damage to the ecosystem.