BHP has said it is still too early to say what caused the tragedy and there has been speculation that there may have been some sort of seismic event. But Minas Gerais state environmental prosecutor Carlos Eduardo Pinto said on Tuesday that the bursting of the dams was "no accident".

"What happened was a mistake in the operation and negligence in the monitoring," Pinto told Brazil's top broadcaster, Globo TV.

The state regulator suspended Samarco's licence on Monday, but Mr Pinto has cited a 2013 document in which he recommended against renewing the company's licence because of concerns about destabilisation and erosion. His recommendation was not followed.

The Minas Gerais state fire department said the body of a five-year-old girl had been found, bringing the official death toll in the accident to four. The number of people missing has been lowered to 22 after one local resident was found on Tuesday.

The disaster has hit the town of Bento Rodrigues hardest and police say 631 people who lost their homes are being housed in hotels in nearby Mariana.

Brazillian president Dilma Rousseff said on Tuesday that she was worried about the red mud from the dams reaching the Rio Doce River. This already appears to be happening, as the sludge is already reaching the neighbouring state of Espirito Santo.

Espirito Santo governor Paulo Hartung said at a news conference that water utilities in the state could suspend siphoning operations on the river in the coming days.

Anger about who is to blame is rising amongst locals.

'Take responsibility'

"Samarco is just a name they made up," Duarte Junior, the mayor of the town of Mariana and the man who has coordinated relief efforts, told Reuters. "We need BHP and Vale to take responsibility for this tragedy."

BHP chief executive Andrew Mackenzie held a news conference in the hours following the disaster and has flown to Brazil, but Vale is under fire for releasing only a five-sentence statement about 24 hours after the dams collapsed.

Vale's chief executive, Murilo Ferreira, made an unannounced visit to Mariana on Saturday, which the company revealed two days later.

Influential Brazilian newspaper columnist Miriam Leitao excoriated the company on Tuesday for its "absolutely insufficient" response.

"Vale has been drilling and dumping around Minas Gerais for 70 years," Leitao wrote in newspaper O Globo.

"After a disaster of this scale, it can't issue a laconic statement as if it weren't obliged to act immediately."

The potential costs of the clean-up and any compensation have been estimated at $US1 billion ($1.42 billion) by Deutsche Bank. Reuters reported that insurers could pay up to $US600 million in claims, citing a source with direct knowledge of the matter.

Samarco's bond rating was cut to junk on Tuesday by Moody's Investors Service. Its $US2.2 billion of notes, which have lost a third of their value since November 5, now trade at US56¢ on the dollar.

- with wires