MOSCOW, February 2. /TASS/. Moscow’s Lefortovo district court on Friday granted the FSB’s motion to extend the period of detention of Norwegian national Frode Berg, who is accused of spying on Russia, according to TASS correspondent.

"The pre-trial detention of Frode Berg to be extended until May 5," the judge announced.

The hearing on the motion was held in a closed-door court session due to the case’s classified material. The media were let in only for the announcement for the resolutive part of the decision therefore the motives of the court remain unknown.

After the hearing, Berg’s lawyer Ilya Novikov told reporters that he had applied for a mitigation of the pre-trial restraint, however due to the denial of the district court he is going to file a complaint with the appellate body of the Moscow City Court.

"The defense is going to appeal the decision," the legal representative said, refusing to comment on the specific circumstances of the case.

Berg has been charged with espionage under section 276 of Russia’s Criminal Code. According to media reports, he was detained in Moscow during a special operation by the FSB upon illegally acquiring classified documents. Detectives believe that these documents, related to the Russian Navy, were handed over to Berg by former Russian policeman Alexey Zhitnyuk, who was arrested at the end of November by the Lefortovo District Court on charges of high treason (under Section 275 of Russia’s Criminal Code).