A Russian detained in Norway on suspicion of illegal intelligence activities at the Norwegian parliament can be held for two weeks, a Norwegian court ruled on Wednesday.
The Borgarting Court of Appeals said there was evidence that Mikhail Bochkaryov had collected information from computer and wireless networks at the parliament last week, upholding adecision by a lower court.
Assurances by the Russian Embassy in Oslo that he would not leave the country without permission if released were insufficient, it added.
"It is not probable that the suspect acted alone," it said.
The Russian foreign ministry has demanded Norway lift "the absurd charges" and release Bochkaryov, whom it identified as a staff member of the Russian parliament's upperhouse.
Bochkaryov was detained on Friday at Oslo airport as he prepared to fly out after attending an international seminar on digitalisation at Norway's parliament.
Norway's police security service, the PST, told Reuters it had asked to be allowed to hold the Russian for two weeks to prevent destruction of evidence, while the parliament's administration took preventive measures in case security had been breached.
Hege Aakre, Bochkaryov's lawyer, told Reuters her client denied any wrongdoing and regarded the incident as a"misunderstanding". There was "no basis for the suspicion against him".