Employees of the Russian Embassy, whose expulsion was announced by Norway this week, tried to recruit new informants, conduct radio reconnaissance and buy advanced technology.
Representatives of the Norwegian Police Security Service (PST) said this during a briefing, NRK reports.
According to Norwegian law enforcement officers, the expelled embassy employees actually worked for the special services of the Russian Federation.
"We are sure. These people are intelligence officers under diplomatic cover," said PST counterintelligence chief Inger Haugland.
According to Norwegian counterintelligence, two sectors are particularly vulnerable - defense and oil.
"Russia uses its consulates and embassies to conduct radio-electronic intelligence. We have no reason to believe that they do this in Norway any less than in other countries," Haugland said.
The main task of one of the expelled Russians was to recruit informants.
The Russians also tried to purchase goods and technologies from Norway that could help build Russian potential.
All 15 unwanted Russians must leave Norway soon.