Officers had discovered a post on an online platform that called for the "elimination" of multiple people and proposed organising an assassination attempt against leading politicians, the bureau said in a statement. The post appeared in a group dedicated to firearms.

"The prosecutor charged the man with undertaking activities aimed at creating conditions for an act directly aimed at committing genocide, with preparing for crimes against peace, humanity and war crimes, as well as with publicly inciting to commit a crime," the Central Bureau for Combating Cybercrime said in a statement.

Polish authorities did not specify who had allegedly been targeted. But Mariusz Boron, a prosecutor, told reporters that the author of a post on Telegram had been "preparing a terrorist attack on leading politicians" and that the alleged targets were from Poland's two largest parties.

The suspect, a resident of the eastern Lublin region, was placed in detention for 30 days by a court. He faces up to 20 years in prison.

(Reporting by Pawel Florkiewicz and Anna Koper; Editing by Sharon Singleton and Timothy Heritage)