According to the newspaper VG, the man in question allegedly has a background from Russian intelligence service. He is now being interrogated by the Norwegian Police Security Service (PST).
The 53-year-old was hired on as an attaché, the least important position at the embassy, when he defected mid May.
Alexander Zinoviev, press attaché at the Russian Embassy confirms to VG that the man in question defected the same day he was about to start his job at the embassy.
According to the newspaper, several agencies that the Norwegian Police Security Service co-operates with, particularly the British Intelligence Service MI6, have indicated a keen interest in the defector.
The 53-year-old is the first Russian diplomat who has defected to Norway since the fall of the Soviet Union. He is allegedly at an undisclosed location in the eastern part of Norway.