The company, which is one of the largest aluminium producers in the world, said that it didn't know the full extent of the attack but said it was working to contain and neutralize the attack in a statement.
"IT systems in most business areas are impacted and Hydro is switching to manual operations as far as possible," it said in a statement. The company's shares are down 2.1% as of 8.50 a.m in London (4.50 a.m ET) while aluminium prices are up 1.5%.
Cyber attacks are an increasingly problematic area for businesses, with a number of high profile breaches causing major infrastructural problems and causing massive data losses. Hacker groups have in the past successfully infiltrated servers of energy companies and the U.S. power grid, with attacks on companies as well including Marriott International, Yahoo! and Anthem .
"We are working to contain the situation and reduce impact, aiming to resume normal operation," Norsk said in an emailed statement to Business Insider.
The attack comes while Norsk attempts to restarts its Alunorte plant in Brazil amid claims of environmental damages after flooding. The company's share price has fallen by almost 40% in the last 13 months following a court-ordered shutdown following a spill at one of its plants, according to Reuters.
Earlier this week the company announced a new CEO in the form of Hilde Merete Aasheim who starts on May 8.
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