LONDON, July 23 (Reuters) - BHP Group ( BHP ) 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.