Russian spies are particularly focusing on Norway's strategic geopolitical position and the country's offshore oil and gas expertise, Aftenposten reported Friday.

The Russians have rivals in the spy game in Norway, PST head Jorn Holme told Aftenposten.

"I'm not going to comment on individual countries," he said, "but there are more countries active (in espionage) in Norway than people would think."

The increased espionage activity follows a relative lull during the 1990s, the report said. Citing unnamed sources, Holme told the newspaper Russian espionage in Norway is at an "all-time high."

There are also unresolved border issues, largely involving natural resources, between Russia and Norway.

Jakub Godzimirski, a researcher at the Norwegian Institute of International Affairs, told the newspaper Russia does not regard Norway as a military threat, but he said Norway is "interesting because it is a member of NATO and the Kremlin sees Norway as an American outpost."