According to Nordea spokesperson Marko Mettenranta, the bank has been in touch with the police regarding the matter and measures are underway to fix it.
Nordea says that the attack has not affected the use of its credit or debit cards or other services.
On Friday morning Nordea said that its online banking services had been more sluggish than normal.
Nordea's online banking may work more slowly than normal. Fixing the problem and additional security measures may result in service interruption, according to Nordea's website. Mobile banking services are said to be working normally.