BHP and 50-50 joint-venture partner Vale had agreed on a $2.3billion settlement in March, but Brazil's Superior Court has responded to an appeal from the Federal Prosecutor's Office by issuing an interim order suspending its ratification.

That decision reinstates a 20 billion real ($6.23 billion) public civil claim for clean-up costs and damages against Samarco, Vale and BHP.

"BHP Billiton Brasil intends to appeal the decision of the Superior Court of Justice," BHP said in a statement. In the meantime, Samarco will continue to support the long-term recovery of the communities and environment affected by the dam failure, the company said.

A burst tailings dam at the mine on November 5 unleashed a mudflow that killed 19 people, left hundreds homeless and polluted a major river. The government called it the country's worst ever environmental disaster.

The mine has been closed since. Environmental authorities say it will only be allowed to reopen when it can prove mud is no longer leaking into the surrounding area and that the mine can be run safely.

($1 = 3.2127 Brazilian Reais)

--reuters--