Authorities in Poland have detained a man suspected of being a member of a Russian spy network, Interior Minister Mariusz Kaminski said on Friday.

The latest arrest brings the total number of people held as part of an investigation into Russian espionage to 16.

"Belarusian Mikhail A. took part in reconnaissance of military facilities and ports. He also carried out propaganda activities for Russia. He was taken into custody," Kaminski wrote on messaging platform X, formerly known as Twitter.

The Polish government said in a statement on Friday the detained man entered the country in 2021 and "maintained contacts with citizens of the Russian Federation, with whom he was meeting in Saint Petersburg and Crimea."

"The man often changed the means of communication and was destroying traces of his criminal activities," the statement added, saying that the 39-year-old suspect pleaded "partly guilty."

In June, Poland also detained a Russian ice hockey player on spy charges.

Russians, Belarusians in Lithuania declared national security risk

Also on Friday, Lithuania declared more than a thousand citizens of Russia and Belarus living in the country to be threats to national security.

The Migration Department said 910 were Belarusian citizens and 254 were Russian citizens.

The country said it was stripping them of their permanent residency permits after asking Russians and Belarusians to fill out a questionnaire that sought their views on Russia's invasion of Ukraine and the status of Crimea, the Ukrainian territory which Russia annexed in 2014.

Those deemed to be national security threats are only a fraction of the 58,000 Belarusians and 16,000 Russians living in Lithuania, which has become a place of refuge in recent years for many who have fled repression in their home countries.

Poland, Lithuania tighten security at Belarus border

Poland and Lithuania announced Thursday they were boosting security at their borders with Belarus following a meeting between both countries' leaders in the Polish border town of Suwalki.

The decision follows the recent arrival of thousands of fighters of the Russian mercenary army Wagner in Belarus after their failed mutiny against Moscow last month.

Over the past two years, Belarusian leader Alexander Lukashenko allowed migrants and refugees from the Middle East and Africa to transit his country and try to cross into Lithuania and Poland — both EU members.

Warsaw is concerned that the Wagner fighters, some of whom are stationed close to the Polish border, may take control of migrant smuggling and even try to enter EU territory along with the migrants.

Polish Prime Minister Mateusz Morawiecki said Warsaw was sending additional soldiers, border guards and police to the frontier and strengthening border fortifications.

Borders could be shut

Lithuanian President Gitanas Nauseda, meanwhile, did not rule out the possibility of closing borders with Belarus in a coordinated manner if necessary.

"One thing is absolutely clear — it would be too great a temptation for Vladimir Putin and Alexander Lukashenko not to use their [Wagner's] presence in the immediate neighborhood for possible provocations against NATO states," Nauseda said.

Earlier this week, Warsaw announced two Belarusian military helicopters had violated Polish airspace, which also prompted the decision to reinforce its eastern border.

mm/wd (AFP, AP, Reuters)