OSLO, March 19 (Reuters) – Norwegian aluminium maker Norsk Hydro on Monday said Brazilian authorities had uncovered additional unregulated spills into a local river from its Alunorte alumina refinery. Additional discharges of untreated rainwater from the roof of a coal storage shed were discovered in a subsequent investigation by authorities, Hydro said, adding that the company had found a separate unregulated spill. “We have discharged untreated rain and surface water into the Para River. This is completely unacceptable and in breach with what Hydro stands for,” Chief Executive Svein Richard Brandtzaeg said in a statement. Hydro on Friday apologised to the local community and announced investment of 500 million Norwegian crowns ($64.65 million) in water treatment systems to prevent a recurrence of the initial spills. On Monday, the company again apologised. It said it would expand an ongoing review by an environmental consultancy and that Hydro’s own internal audit unit would get involved. Last month Brazil ordered Hydro to halve its output from the plant, the world’s largest of its kind, after spills were made during heavy rain, prompting the company to declare force majeure.