A burst dam at an iron ore mine owned by Vale and BHP Billiton left at least two people dead, more than 30 injured and dozens missing overnight, a spokesman for firefighters in the city of Mariana said on Friday.

The dam had been holding back waste water at the Germano mine operated by the firms' Samarco joint venture, and the disaster unleashed a mudslide that destroyed hundreds of homes in a nearby village on Thursday.