(Adds prosecutor criticism of settlement between Samarco and government)
RIO DE JANEIRO, May 3 (Reuters) - Federal prosecutors in Brazil filed a 155 billion-real ($43.5 billion) civil lawsuit on Tuesday against iron miner Samarco, and its owners, Vale SA VALE5.SA and BHP Billiton BLT.L , for a collapsed tailings dam in November that killed 19 people and polluted a major river.
The 359-page lawsuit, which is also against the two states affected by the spill and the federal government, is the result of a six-month investigation led by a task force set up after the disaster, prosecutors said in a statement.
Vale said it had not been notified of the suit and was therefore unable to comment. BHP did not immediately respond to a request for comment.
The total damages, prosecutors said, were 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.
Prosecutors demanded an initial payment of 7.7 billion reais.
The civil action is separate from the lawsuit that Samarco, Vale and BHP settled with Brazil's government in March in which the companies would pay an estimated 20 billion reais for damage caused by the spill. Federal and state prosecutors did not form part of that settlement.
The settlement itself was criticized by prosecutors, who said it was insufficient and lacked the legal mechanisms to ensure the companies would fulfill their obligations, making it little more than a "letter of intent."
The roles of the state and federal government were also questioned, with prosecutors accusing the state of Minas Gerais, where the spill occurred, as being guilty of negligence in the permitting and monitoring of the dam.