Norway is to release a Russian man held on suspicion of spying, police tweeted on Friday.

Mikhail Bochkaryov was detained on Sept. 21 at Oslo airport as he was about to fly out after attending an international seminar on digitalization in Norway's parliament.

He has denied any wrongdoing and the Russian Foreign Ministry has demanded that Norway drop "the absurd charges" and release Bochkaryov, whom it identified as a member of staff in the Russian parliament's upper house.

Norway's Police Security Service (PST) had originally sought to extend his detention, but the Oslo District Court on Thursday rejected the request, triggering an immediate appeal by prosecutors.