Mining company BHP has been found liable for a 2015 dam collapse in Brazil, known as the country's worst-ever environmental disaster, by London's High Court.
The dam collapse killed 19 people, polluted the river and destroyed hundreds of homes.
The civil lawsuit, representing more than 600,000 people including civilians, local governments and businesses, had been valued at up to £36bn ($48bn).
BHP said it would appeal against the ruling and continue to fight the lawsuit and has said many claimants in the London lawsuit had already been paid compensation in Brazil.
The dam in Mariana, southeastern Brazil, was owned by Samarco, a joint venture between the mining giants Vale and BHP.
The claimants' lawyers argued successfully that the trial should be held in London because BHP headquarters were in the UK at the time of the dam collapse.
A separate claim against Samarco's second parent company, Brazilian mining company Vale, was filed in the Netherlands, with more than 70,000 plaintiffs.
The dam was used to store waste from iron ore mining. When it burst, it unleashed tens of millions of cubic metres of toxic waste and mud, poisoning the river and causing tremendous devastation to local communities.
Judge Finola O'Farrell stated that the continued elevation of the dam despite safety risks was the direct and immediate cause of the collapse, implicating BHP under Brazilian law.
BHP is expected to contest the ruling vigorously, maintaining that most claimants in the London lawsuit have already received compensation from previous arrangements in Brazil.
The legal battle has been complicated by accusations against the law firm representing the claimants, Pogust Goodhead, alleging that it sought to profit from vulnerable populations by misleading them.
The claims against BHP contribute to an ongoing discussion about corporate responsibility, ecological preservation, and the rights of affected communities in the aftermath of environmental disasters.
