The 2015 dam collapse killed 19 people and unleashed a deluge of thick toxic mud into villages, fields, rainforest, rivers and the ocean.

The Fundao tailings dam at an iron ore mine in the mountains of Minas Gerais state was managed by Samarco, co-owned by BHP and Brazilian miner Vale.

The London High Court hearing that began in October heard evidence on behalf of BHP and hundreds of thousands of claimants in relation to the dam collapse that may trigger a payout worth billions of pounds (dollars).

Should the court later this year rule that BHP is liable, a further trial would be held to determine the amount of compensation.

At the time of the disaster, BHP had global headquarters in Britain and Australia.

A separate case in Brazil has seen Vale and BHP offer to pay around $30 billion in compensation. This was increased around the start of the London trial from almost $25 billion.

"We are extremely confident of succeeding in this trial," Tom Goodhead, of law firm Pogust Goodhead which brought the case, told AFP as the preliminary hearing prepared to conclude.

More than 620,000 complainants, including 46 Brazilian municipalities, companies and indigenous peoples, are seeking an estimated pound36 billion ($47 billion) in damages in the civil trial.

BHP has argued that it cannot be deemed to be the "direct polluter" as the dam was managed by Samarco.

"The Samarco Fundao dam failure in 2015 was a tragedy, and our sympathies will always be with the impacted families and communities," a BHP spokesperson said in a statement to AFP ahead of Thursday's conclusion.

"We are confident in our legal position in the UK and the evidence submitted, which shows we prioritised safety and acted responsibly.

"We will continue to defend our case while respecting the UK legal process," they added.

- 'Hopeful of justice' -

The tragedy in the town of Mariana unleashed almost 45 million cubic metres (1,590 million cubic feet) of highly toxic mining waste sludge, flooding 39 towns and leaving more than 600 people homeless.

"BHP needs to be held accountable and pay for all the damage and suffering it has caused us all this time," Monica dos Santos, who lost her home, said in a statement.

"I have a lot of faith in British justice to deliver the justice we've been waiting for years. It is our only hope."

According to the victims' lawyers, BHP was aware that an accumulation of toxic sludge, estimated at 1.3 million tonnes per year, far exceeded the annual limit set -- a build-up which they say contributed to the disaster.

BHP and Vale estimate that more than 430,000 complainants have already received compensation, including more than 200,000 party to the London case.

BHP added that the Renova Foundation, which manages compensation and rehabilitation programmes, has already paid out more than $7.9 billion in emergency aid.

The Australian mining giant has also said that the quality of river water contaminated by the fallout has returned to pre-disaster levels.

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