The Samarco mine has been shut since November 2015, when a dam burst, unleashing a deluge of mud that killed 19 people and destroyed nearby towns.

A columnist in the respected O Globo newspaper reported on Sunday that BHP wants to sell its stake and Vale wants to buy it. The column said the decision has been made.

"It is something that will take more than six months to close," the column said.

BHP spokesman Ben Pratt said the report was "incorrect".

"There has been no agreement," he said.

Asked whether BHP was looking to sell its stake, Pratt said: "We remain committed to the long-term remediation of the Samarco project."

Vale declined to comment.

BHP and Vale face a 155 billion real ($50 billion) claim to clean up the country's worst environmental disaster.