Massive lawsuit over Brazilian mine disaster

The 359-page civil lawsuit filed Tuesday also names the two states affected by the spill and is the result of a six-month investigation led by a task force set up after the disaster, prosecutors said in a statement.

Prosecutors are asking for 155 billion Brazilian reals ($43.5 billion) against Vale SA and the Anglo-Australian giant BHP Billiton for a collapsed tailings dam in November that killed at least 17 people and polluted a major river.

The amount now being claimed is dwarfs the $6.2 billion settlement agreed with authorities in March, which is yet to be ratified in court.

BHP Billiton - whose stock price plummeted 7 percent on Wednesday - said it remained committed to the earlier deal.

"We believe that the agreement (once approved by the court) provides the long-term remedial and compensation framework for responding to the impact of the Samarco tragedy and the appropriate platform for the parties to work together," BHP said in a statement.

Prosecutors say the new total was calculated based upon the cost of the Deepwater Horizon oil spill in the United States. BP's total pre-tax charge for that spill reached $53.8 billion.

Federal and state prosecutors were not party to the March settlement, which has been criticized as insufficient and lacking the legal mechanisms to ensure the companies would fulfill their obligations, making it little more than a "letter of intent."

Unprecedented destruction from an iron ore mine

The November disaster near Mariana in Minas Gerais state began November 5, 2015 when a tailings dam at Samarco's mine failed, unleashing the flood of polluted water and mud into the Rio Doce.

A village was destroyed, drinking water supplies for hundreds of thousands of people were affected and damage reached as far as the river's mouth on the Atlantic coast, with damage to wildlife, tourism businesses and fishing communities.