Police were expected to formally accuse eight to 12 people from both companies for the crime of false representation, a person familiar with the probe told the Wall Street Journal.

"The accused individuals invented an inadequate methodology to justify giving the dam the minimum safety rating," the person said.

A TÜV SÜD spokeswoman told the paper the company wouldn't comment on the case but had cooperated fully with the authorities in the investigation, while a spokeswoman for Vale declined to comment but the company has said it had no knowledge of any imminent risk at the dam, and had cooperated fully with authorities.

Vale was convicted for damages by a Brazil court over the Brumadinho disaster in July, with the judge not specifying a value because it was not limited to the deaths but also the environmental and economic impacts.

The official death toll at the start of this month was 249, with 21 people still missing. 

The miner's operations have come under increasing scrutiny, with partial operations at its second-largest iron ore mine, Brucutu, suspended again this month.

Vale's curbed production and setbacks at BHP's and Rio Tinto's Pilbara iron ore operations earlier this year helped push the iron ore price to a five-year high above US$120 per tonne in July.