OSLO (Reuters) - Hackers demanded ransom money from Norsk Hydro to stop an ongoing cyber attack on its IT systems, public broadcaster NRK reported on its website, citing a message sent by the Norwegian National Centre for Cybersecurity.

The Norwegian National Security Authority, of which the Norwegian National Centre for Cybersecurity is a part, was not immediately available for comment.

Norsk Hydro was not immediately available for comment.