WARSAW (Reuters) - Poland has detained a Russian woman who was part of a pro-Russian group that sought to whip up tension between Poland and Ukraine and will expel her soon, the national agency for internal security ABW said on Thursday.

Four other people involved in what the ABW described as “hybrid” activities against Poland would be banned for five years from entering Poland, the ABW said. ABW identified the Russian woman as “Yekaterina C.”.

It did not elaborate on the identities of the four other people which it said had undertaken “determined attempts to consolidate pro-Russian groups in Poland around two key priorities of Russia’s hybrid actions against Poland.”

“That is fuelling Polish-Ukrainian animosities in social and political spheres as well as undermining interpretation of Polish history and replacing it with a Russian narration,” the ABW said.

There was no immediate comment available from Russia.

Hybrid warfare includes conducting foreign disinformation campaigns, such as spreading fake news, and targeting the public at crucial times such as elections and in diplomatic or other crises.

ABW said its intervention had “neutralized the activity of two network structures taking part in the Russian hybrid and information war carried out against Poland”.

Poland, a member of NATO and the European Union, views Russia as the biggest threat to its security, especially since Russia annexed the Crimean peninsula from Ukraine in 2014.