BHP Billiton said Tuesday it was reviewing a judge's decision to freeze its Brazilian assets to ensure reparations are paid for a deadly toxic dam burst, after fellow miner Vale vowed to appeal the ruling.

The Anglo-American mining giant and Brazil's Vale are co-owners of Samarco, the operator of an iron ore mine in Minas Gerais state where a waste-water dam collapsed in early November, killing 17.

"We are reviewing the decision and considering options, including any grounds for appealing the decision," a BHP spokesman said in a statement about the ruling to put on hold BHP's and Vale's Brazilian assets.

Vale said Monday it would appeal the Friday ruling, calling it "baseless".

Brazil plans to sue Vale and BHP Billiton for US$5.2 billion for clean-up costs and damages relating to the incident, considered one of the nation's worst ever environmental disasters.

BHP added that two people who worked on the dams remained missing.

The miner said it had jointly appointed with Vale and Samarco a New York-based law firm, Cleary Gottlieb Steen & Hamilton, to investigate the cause of the dam rupture.

"BHP Billiton has committed to release publicly the findings of the external investigation, and to sharing the results with other resources companies," said the mining firm, one of the world's biggest.

Brazil's Environment Minister Izabella Teixeira has said it would take at least a decade for conditions to return to normal in the river basin.

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