Brazil dam disaster: firm knew of potential impact months in advance

Unreported documents show mining company was aware of threat before country's worst environmental disaster but took no action, prosecutors allege

Six months before a dam containing millions of litres of mining waste collapsed, killing 19 people in Brazil's worst environmental disaster, the company operating the mine accurately predicted the potential impact of such a disaster in a worst-case risk assessment.

But federal prosecutors claim the company - a joint venture between the Brazilian mining giant Vale and the Anglo-Australian multinational BHP Billiton - failed to take actions that they say could have prevented the disaster. The prosecutors instead claim the company focused on cutting costs and increasing production.