"BRASILIA -- Brazil filed a lawsuit on Monday against two of the world's largest mining companies for 20 billion Brazilian reais ($5.2 billion) to clean up what it says was its worst environmental disaster, caused by the collapse of a tailings dam.

The governments of Brazil and those of two states hit by the damburst sued iron ore operator Samarco and its co-owners, the world's largest miner BHP Billiton Ltd and the biggest iron ore miner Vale SA.

Earlier on Monday, President Dilma Rousseff blamed the disaster on the 'irresponsible action of a company' in a speech to the COP21 climate change summit in Paris. 'We are severely punishing those responsible for this tragedy,' she said."

Anthony Boadle reports for Reuters November 30, 2015. [2]