A number of private and public institutions in Norway have been subjected to a so-called distributed denial-of-service (DDoS) cyberattack in the last 24 hours, the Norwegian NSM security authority said on Wednesday.
"A criminal pro-Russian group appears to be behind the attacks," NSM said in a statement.
The attacks targeted institutions offering important services, the agency said, but did not name any of those that were affected.
The website of the Norwegian Labour Inspection Authority was unavailable on Wednesday and Norwegian media reported that it had been among those subject to the attack.
"We've seen similar attacks in other countries recently although none of them have reported any lasting impact," NSM director Sofie Nystroem said.
"This can still spread uncertainty in the general population," she added.