(Reuters) - The world’s largest alumina refinery in Brazil, Alunorte, has declared force majeure after authorities ordered it to halve its production over fears of water contamination, its owner Norwegian Norsk Hydro said on Friday.

Brazilian authorities ordered the plant to cut production and stop operations at its bauxite residue deposit after heavy rainfall caused flooding in Barcarena, where Alunorte is located.

Force majeure was also declared due to lack of clarity over what measures it would take to return the plant, which has a capacity to produce 6.3 million tonnes of alumina per year and employs around 2,000 people, to normal operations, Norsk Hydro said in a statement.

“Hydro, as the largest offtaker of alumina from Alunorte, is taking and assessing a range of possible mitigating actions to minimize the negative effect for its customers,” it added.

Brazilian authorities have taken several measures against the alumina refinery, including orders to cut alumina production and halt operations at its DRS2 bauxite residue deposit, Hydro said.