Independent experts warned two years ago that the jointly owned Samarco mine, which collapsed last week in south eastern Brazil killing at least six people, was not safe.
A 2013 report conducted by The Instituto Pristino linked to the Federal University of Minas Gerais, warned of structural design flaws and predicted the circumstances that could lead to a dam burst at the Samarco operation.
"The report had already highlighted the fragility of these structures and the necessity of increased rigor in monitoring them," Brazilian state prosecutor Carlos Eduardo Ferreira Pinto said.
"No operation of this size just breaks without warning," Pinto added.
The dam's failure caused a massive mudslide that killed at least six people and left 22 missing.
Meanwhile, Brazilian lawmakers are advocating for stricter mining regulations following the disaster, while prosecutors said that negligence by mine co-owners BHP Billiton Ltd. and Vale SA likely caused the incident.
Over three-quarters of Brazil’s energy is supplied by hydroelectric dams. Mining is also a fundamental pillar of the Brazilian economy.
Deutsche Bank's Paul Young says BHP Billiton estimates that BHP and joint venture partner Vale could face costs of at least US$1 billion arising from the failure of a tailings dam at the mine in the state of Minas Gerais