Russia's Federal Security Service (FSB) on Friday said it had arrested a Russian national, working for a state firm, who it said was planning to pass on sensitive information to Poland.

The FSB said the man was working at a "secure facility" in the central Penza region and was held for attempting to pass on information about his workplace to Polish intelligence, state news agency RIA reported.

Poland says FSB claims 'fake news'

Poland's deputy foreign minister Andrjez Szejna poured cold water on the claims in comments carried by Polish news website Onet.

"Any information provided by the Russian side in a situation where we are making every possible effort to support Ukraine... should be considered 'fake news'," Szejna was quoted as saying.

RIA reported that the intelligence services published a video of the interrogation of the man who it said planned to transfer data in exchange for "political asylum."

The video released to Russian news agencies also reportedly showed NATO patches, a copy of the Polish constitution and Ukrainian language books allegedly found in his flat.

The FSB said a criminal case was opened over treason, charges that could carry a maximum penalty of life imprisonment.

Large number of detentions since Ukraine invasion

Russian security services have detained a number of foreigners and Russian nationals on allegations of working with foreign intelligence since launching its invasion of Ukraine in February 2022.

In November a Moscow court extended the detention of Wall Street Journal reporter Evan Gershkovich until later this month.

The US journalist was arrested in March 2023 in Russia on espionage charges and has since had his detention repeatedly extended. Such charges carry a sentence of up to 20 years in prison.

Moscow says will only consider an exchange for Gershkovich after the conclusion of his trial, which could take more than a year.

kb/wd (AFP, AP)