LONDON - BHP Group must stop funding legal action seeking to halt some Brazilian municipalities from bringing a multi-billion pound claim over one of Brazil's worst environmental disasters, London's High Court ruled on Tuesday.

More than 720 000 Brazilians, including around 50 municipalities, are suing BHP over the 2015 collapse of the Mariana dam, which was owned and operated by its Samarco joint venture with Brazilian iron-ore miner Vale.

The dam collapse caused a wave of toxic tailings that killed 19 people, left hundreds homeless, flooded forests and polluted the entire length of the Doce River.

The claimants in June filed an injunction against BHP after Brazilian Mining Association IBRAM filed a motion in Brazil's Supreme Court seeking to stop the municipalities from continuing the London case on the grounds that doing so represented a threat to Brazil's sovereignty.

BHP, the world's biggest miner by market value, is a member of IBRAM and funded it to make the claim at the Supreme Court.

BHP, which has agreed to the order, did not immediately respond to a request for comment.

BHP earlier this month reached a deal with Vale to split equally the cost of any damages related to proceedings in Britain, for which it will continue to be the defendant.

In March, a new claim was filed against Vale and the Dutch subsidiary of Samarco in the Netherlands in which BHP is not a defendant.

The London lawsuit is separate from litigation in Brazil, which mostly addresses claims from local governments and not individuals.

The lawsuit, one of the largest in English legal history, began in 2018. The first trial of key legal issues is due to begin in October.

Vale, BHP and Samarco in June presented Brazilian authorities with a $26.09-billion offer to settle reparations for the dam collapse after Brazil rejected a previous offer.

BHP, which denies liability, has referred to reparation and compensation programmes implemented by the Renova Foundation, a redress scheme established in 2016 by Samarco and its shareholders, which has funded more than $6 billion of rehousing and rehabilitation for those affected by the disaster.