Two Russians convicted of spying have been released by Lithuanian authorities, leading to a three-way spy swap as Russia released a Norwegian national, also held on spying charges.

On Friday morning, Lithuania's president, Gitanas Nausėda, granted pardons to five prisoners. Three were Lithuanians who were rewarded for good behavior in jail, or released on health grounds. But the other two to have their sentences commuted were Russian citizens, imprisoned for spying, and released "based on Article 79(2) of the Penal Code of the Republic of Lithuania." 

The full picture behind their release is not yet clear, as Article 79 simply states: "A convict may be released from serving the entire length of the sentence or a part thereof where the President of the Republic grants his clemency plea."

Nikolai Filipchenko was sentenced in 2017 to 10 years for spying, giving fraudulent information to obtain a document, forging and using personal identification and illegally crossing a state border.

Sergei Moisejenko was sentenced in 2017 to 10-and-a-half years for spying and for illegal possession of weapons.

Since the announcement, the Norwegian government has confirmed to CGTN Europe that Frode Berg, whose case became famous in his native Norway, has been released to Lithuanian authorities, and will be transported back to Norway. 

In 2017, he admitted to working as a courier for Norwegian intelligence services, but denied the charges of spying. He was arrested in Moscow and found to be in possession of materials which were handed to him by a former Russian police official. 

Norwegian Prime Minister Erna Solberg confirmed Berg was handed from Russian to Lithuanian authorities at 11:00 local time, and will now return home to his family. 

"We are very pleased that Frode Berg will now be able to return to Norway as a free man. I would like to thank the Lithuanian authorities for their cooperation and for the work they have done to ensure that Mr Berg could be released," Solberg said.

"The time Frode Berg has spent in prison has put a great strain on him and his family. We have worked systematically to get Mr Berg home ever since his arrest," added Ine Eriksen Søreide, Norway's minister of foreign affairs. 

Reuters news agency has reported discussions may have been ongoing between Moscow, Vilnius and Oslo for at least a month prior to this release. 

The Washington Post reported two Lithuanians, Yevgeny Mataitis and Aristidas Tamosaitis, may be released in return by Moscow. They were sentenced on espionage charges in 2016, and held by Russia since.