According to a statement from prosecutors released late on Tuesday, the deal allows for compensation payments to start to relatives of the 19 people killed in the disaster, as well as to people who lost their houses and other properties.

No financial details of the deal were disclosed in the short statement on Tuesday, but the chief prosecutor in the city of Mariana will hold a press conference on Wednesday to discuss the agreement.

Brazil's worst environmental catastrophe happened when a dam designed to hold back mine waste from the Samarco iron pellets operation in Mariana burst, leaving a trail of destruction for hundreds of kilometres in Minas Gerais and Espírito Santo states.

Another deal had been reached by the mining companies and prosecutors in regions hit by the disaster away from Mariana, where victims found that offer insufficient. With this last settlement, companies might be able to prepare to resume operations in the region more than two years after the accident.

Vale has said it expects the Samarco unit to resume operations in 2018 or early next year, but has pushed back forecasts several times.

The mine still needs permits to reopen, and the lack of a clear timeline makes it harder for the controlling companies to renegotiate the debt Samarco will carry from the disaster.

(Reporting by Marta Nogueira and Marcelo Teixeira; Editing by Toni Reinhold and Richard Pullin)

By Marcelo Teixeira and Marta Nogueira