"Their aim is to destabilize the socio-political situation in our country," Stanislaw Zaryn, the spokesman for the Internal Security Agency, said Thursday.
The announcement came as officials are warning that Russia is seeking to destabilize Poland and exacerbate Polish-Ukrainian tensions in order to weaken Ukraine's alliances with Western powers.
Russia invaded Ukraine and annexed the Crimean Peninsula in 2014 amid a broader effort to reassert its sway in a region that Moscow had controlled until 1989.
Poland's Internal Security Agency, which is focused on investigating espionage and terrorism, said it had detained a Russian woman identified only as Yekaterina C. and would expel her. It said she had been in Poland since 2013.
The agency accused her and the four other Russians of "hybrid" activities, a term used to describe non-military but subversive tactics that Russia is suspected of using to further its interests.
Zaryn said the Polish efforts were aimed at "neutralizing the activity of two network structures involved in the Russian hybrid and informational war" against Poland. The security agency said the Russians were pushing interpretations of history that would incite hatred between Ukrainians and Poles.
Zaryn said the Polish investigation was also targeting Polish citizens who had cooperated with the Russians and were funded for taking specific actions "against Poland and in the interests of Russia."
Poland for many years has been a key supporter of Ukraine's pro-Western ambitions. However, the neighbors remain deeply divided over how to remember a shared past that includes massacres of Poles by Ukrainian nationalists during the German occupation in World War II, but also a longer legacy of Polish colonialism and brutality toward Ukrainians.
Over the past two years, Poland and Ukraine have increasingly been at odds over that history amid a rise of nationalism in both countries.
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