Moscow's Lefortovsky court ruled to detain for at least two months Norwegian citizen Frode Berg on suspicion of spying for a foreign state, spokeswoman Ekaterina Krasnova told AFP.
The hearing had taken place on December 6th and Berg would remain in custody until at least February 5, she added without providing more details.
Russian media reported that Berg had been detained during a sting operation conducted by Russia's FSB security agency in Moscow while receiving classified documents concerning the country's navy.
Citing investigators, media said that Berg had received the documents from a Russian national, Alexei Zhitnyuk, who himself had been earlier arrested for treason.
Russian security services believe Berg had been cooperating with Norwegian security services as well as the Central Intelligence Agency of the United States, Russian media said, citing sources.
The Norwegian broadcaster TV2 said that the 62-year-old used to work at the Norwegian Border Commissioner, a government agency that oversees laws and traffic at the border with Russia.
The Norwegian foreign ministry said the suspect's personal information could not be disclosed "due to rules of confidentiality".
"The citizen has been given legal representation," ministry spokesman Frode Overland Andersen told AFP in emailed comments.
"He will be provided consular assistance in accordance with our guidelines for imprisoned citizens abroad," he added.
Norway, a Nato member, and neighbouring Russia normally enjoy good relations but these have grown more tense since the outbreak of the Ukraine crisis in 2014.
Norway announced last year that 330 US Marines were to be stationed on rotation around 1,000 kilometres from the Russian border.
Russia has said those plans would do nothing to make northern Europe safer.
Norwegian intelligence said earlier this year that the country's foreign ministry, army and other institutions had been targeted in a cyber-attack by a group suspected of having links to Russian authorities.