Signe Aalling of security service PST told reporters that the suspect, a Norwegian citizen, was arrested today for "spreading information particularly geared toward committing acts of terrorism."
She gave no other details and declined to comment on Norwegian media reports saying the man was an employee of engineering firm Aker Solutions.
Norway's TV2 quoted company spokeswoman Bunny Nooryani as saying that an employee had been suspended for violating internal guidelines and that police had arrested the employee today at the company's office in Fornebu, outside Oslo.