Hildebrando Neto, deputy minister for environmental regulations in the state of Minas Gerais where the collapsed dam is based, told Reuters late on Thursday that all evidence suggests that the burst was caused by liquefaction, a process whereby a solid material such as sand loses strength and stiffness and behaves more like a liquid.
At least 65 people have died and a further 279 are missing.
Dramatic footage has emerged showing the moment a mine dam burst in Brazil, leaving 110 people dead and 200 missing.
Vale, the world's biggest producer of iron ore and nickel, said it was co-operating with prosecutors.
This is the second dam disaster in three years to hit Brazilian mining company Vale. Rescuers momentarily stopped looking for bodies and police helicopters released flower petals over the ruined area.
On Saturday, rescue workers were concentrating on an area where there had been a dressing room in which there were numerous people at the time of the disaster, said Pedro Aihara, spokesman for the fire department.
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The camera, according to BandNews TV, was on top of a crane at the mine and captured the scene after the dam breach, which unleashed a massive wall of muddy, mine waste.
With hopes of finding survivors dwindling, talk of how to deal with the 12 million cubic metres of mud released is escalating.
Vale, the company that ran and operated the dam, said the residues did not have risky levels of metals, but experts argue that the impact on the environment could be irreversible.
Employees of the mining complex were eating lunch when the dam gave way.
Hundreds of municipalities and larger cities such as Petrolina, 1400km from Brumadinho, get drinking water from the Sao Francisco River.