Brazil will not take part in the annual meeting of the Organization of American States in Washington on Wednesday due to a dispute over a giant hydroelectric plant, said opponents of the scheme.

"We received a statement from the permanent mission to to OAS on Friday evening and reports that Brazil will not be represented at the meeting," said lawyer Andressa Calgas, director of support group Global Justice, at a press conference in Rio de Janeiro.

In the statement, Brazil reiterated that all social and environmental protection measures related to the $11 billion project in western Para state, along the Xingu river in Brazil's Amazon rainforest project should be met.

The decision not to appear at the meeting "shows the cowardice of the government" that "wants to avoid being publicly blamed," Calgas said.

Environmentalists and activists for Brazil's indigenous peoples on September 29 cheered a federal court order halting construction at the controversial dam.

Government officials said they would appeal the decision on the project, which is a centerpiece of efforts to boost energy production in the rapidly growing economy but has drawn criticism both at home and abroad for its impact.

The Belo Monte dam would be the third biggest dam in the world, after China's Three Gorges construction and the Itaipu dam on the border of Brazil and Paraguay.

It would produce more than 11,000 megawatts, or about 11 percent of Brazil's current installed capacity.

The project is expected to employ 20,000 people directly in construction, flood an area of 500 square kilometers (200 square miles) along the Xingu river and will displace 16,000 people.