A dam collapse in 2015 unleashed tonnes of toxic waste into a major river, killing 19 and devastating villages downstream.

A judge in the United Kingdom has ruled that global mining giant BHP Group is liable in Brazil’s worst environmental disaster, in a lawsuit the claimants’ lawyers previously valued at up to 36 billion pounds ($48bn).

High Court Justice Finola O’Farrell said on Friday that Australia-based BHP was responsible despite not owning the dam at the time.

A dam collapse 10 years ago unleashed tonnes of toxic waste into a major river, killing 19 people and devastating villages downstream.

Anglo-Australian BHP owns 50 percent of Samarco, the Brazilian company that operates the iron ore mine where the tailings dam ruptured on November 5, 2015. Enough mine waste to fill 13,000 Olympic-size swimming pools poured into the Doce River in southeastern Brazil.

Sludge from the burst dam destroyed the once-bustling village of Bento Rodrigues in Minas Gerais state, badly damaged other towns, left thousands homeless and flooded forests.

The disaster also killed 14 tonnes of freshwater fish and polluted 600km (370 miles) of the Doce River, according to a study by the University of Ulster in the UK. The river, which the Krenak Indigenous people revere as a deity, has yet to recover.

O’Farrell said in her ruling that continuing to raise the height of the dam when it was not safe to do so was the “direct and immediate cause” of the dam’s collapse, meaning BHP was liable under Brazilian law.

BHP said it would appeal against the ruling and continue to fight the lawsuit. BHP’s President Minerals Americas Brandon Craig said in a statement that 240,000 claimants in the London lawsuit “have already been paid compensation in Brazil”.

The case was filed in the UK because one of BHP’s two main legal entities was based in London at the time.

“They say this sets a precedent for how multinational corporations operate from now on, that they can be held liable … even if their operations are in other countries,” Al Jazeera’s Monica Yanakiew said, reporting from Rio De Janeiro, Brazil.

The trial began in October 2024, just days before Brazil’s federal government reached a multibillion-dollar settlement with the mining companies.

Under the agreement, Samarco – which is also half-owned by Brazilian mining giant Vale – agreed to pay 132 billion reais ($23bn) over 20 years. The payments were meant to compensate for human, environmental and infrastructure damage.

BHP had said the UK legal action was unnecessary because it duplicated matters covered by legal proceedings in Brazil.