A dam collapse in 2015 at an iron-ore mine run by a firm co-owned by BHP killed 19 people and unleashed a deluge of thick toxic mud into villages, fields, rainforest, rivers and the ocean.

The victims first filed the UK legal action in 2018 to demand compensation from BHP -- at the time of the disaster, one of its global headquarters was in Britain.

The eventual trial at the High Court in London ran from October 2024 to March this year, and the court has already begun preparing the second phase of the case to determine potential damages and compensation if BHP is found liable.

According to the victims' lawyers, BHP was aware that toxic sludge was accumulating at at the facility in Minas Gerais state north of Rio de Janeiro at rates that far exceeded the annual limit.

The lawyers said the build-up contributed to the disaster at the mine, which was managed by Samarco, co-owned by BHP and Brazilian miner Vale.

BHP argued during the trial that it had prioritised safety and acted responsibly.

Acknowledging the "terrible tragedy", BHP maintained that a compensation agreement it reached last year in Brazil -- worth around $31 billion -- provided a resolution.

However, a majority of the 620,000 claimants, including 31 municipalities, argue that they are not sufficiently covered by the deal.

Instead, claimants are seeking around pound36 billion ($47 billion) in compensation, according to a previous estimate from law firm Pogust Goodhead.

The city of Mariana, one of the areas hardest hit by the disaster, is seeking tens of billions of Brazilian reais in compensation.

Vale and BHP were acquitted in November 2024 of criminal charges by a Brazilian court, which ruled there was insufficient evidence linking them to the dam's failure.

"I'm here for justice," Pamela Fernandes, who lost her five-year old daughter Manu in the tragedy, told AFP at the trial in March.

"I will feel relief when I hear that the company will pay for what it did," she said.

Meanwhile, another similar civil lawsuit has been ongoing since 2024 in the Netherlands.