(Bloomberg) -- BHP Group Ltd. may face a £36 billion ($44 billion) compensation payout if it loses a London class action lawsuit over its role in the deadly collapse of a Brazilian dam. 

Pogust Goodhead, the lawyers behind the so-called opt-in class action suit, said the newly calculated damages bill has soared after an additional 500,000 claimants joined the case. It’s the world’s largest case of its kind with total claimants now exceeding 700,000, plus 46 Brazilian municipalities, businesses and indigenous people, they said.

The Fundão Dam collapsed in 2015, unleashing a torrent of mud filled with toxic mine waste and killing 19 people in Mariana, Minas Gerais. The flood destroyed entire villages, polluted rivers and devastated natural habitats. The payout estimate is based on the claimants’ own calculations and any possible final compensation would be decided at a separate hearing after the trial. It includes annual interest of 12% every year since the tragedy.

“Not only have BHP failed to provide full and fair compensation to our clients, but they have exposed their investors to extraordinary levels of risk in relation to the unprecedented compensation bill BHP faces in England, not to mention their liabilities in Brazil,” said Tom Goodhead, Pogust Goodhead’s global managing partner.  

London judges paved the way for the group to bring a suit against BHP last year after it overturned a lower court ruling blocking it from taking place in the UK. BHP, which is UK listed, had argued that the case duplicates legal proceedings in Brazil and shouldn’t be allowed to go ahead. The trial is set for April 9 2024. 

“BHP will continue to defend the UK group action and denies the claims in their entirety,” a company spokesperson said. “The UK claim is at a preliminary stage with full details of claim yet to be provided and no damages quantified for most of the claims.”

Goodhead said that the law firm remains hopeful that a settlement can be agreed before the case reaches trial in 2024. 

“BHP came to my house, took my food, soiled my water and tried to erase our identity,” said Maykon Krenak, one of the claimants from the Krenak community. “We want justice.” 

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