Demonstrators displayed signs at the mine entrance complaining of the "impunity" of the company and its shareholders over what is regarded as one of Brazil's worst environmental disasters.

The collapse of the Fundao tailings dam near the town of Mariana caused a vast flow of mud and mining waste that buried a nearby village and polluted a major river.

State prosecutors last month filed a lawsuit seeking 2.5 billion reais ($457 million) from Vale and BHP related to the incident, alleging that they had not fulfilled the obligations outlined in a settlement agreed in 2018.

Samarco said it is complying with the terms of an agreement with prosecutors reached in 2016, and has made payments to more than 336,000 people. It said the protesters were outside the unit and that the demonstration has not disrupted production.

(Reporting by Roberto Samora; Writing by Tatiana Bautzer; Editing by Jan Harvey)

By Roberto Samora