Poland has arrested a Russian man who was hired by Moscow to kill a Ukrainian-American citizen ​in Warsaw, Polish Prime Minister Donald Tusk said ‌on Thursday.

The Russian was detained on August 7 and had been recruited to kill a man who was "inconvenient to ​the Putin regime", Tusk told journalists.

The Russian ​embassy in Warsaw did not immediately respond ⁠to an emailed request for comment. Moscow has ​regularly dismissed accusations by European powers of attacks, saying ​the West is stoking anti-Russian paranoia.

"Thanks to the truly brilliant action of our services ... we detained a Russian citizen recruited ​by Russian intelligence services," Tusk said.

The Russian had ​been hired to kill a man who had both Ukrainian ‌and ⁠U.S. passports, Tusk said, without giving any more information on his identity.

"At the last minute, thanks to the action of the Internal Security Agency and ​the police, we ​managed to ⁠prevent this execution, this attack," Tusk added.

In June, a Russian artist critical of President ​Vladimir Putin was shot and killed in ​the ⁠eastern Polish town of Biala Podlaska, prosecutors said.

Poland says its role as a hub for military and other ⁠supplies ​to neighbouring Ukraine has made ​it a target for Russian espionage and attacks.