Polish Prime Minister Donald Tusk has accused Russia of planning acts of sabotage worldwide including “acts of air terror” against airlines.

The pro-European Union government in Warsaw says Russia is pursuing acts of hybrid war against Poland and other Western countries in retaliation for their support of Ukraine.

The Kremlin said on Thursday that an allegation by Polish Prime Minister Donald Tusk that Russia had planned "acts of terrorism" in the air against Poland and other countries was completely unsubstantiated.

The Russian missiles sought out targets from the Lviv region in western Ukraine near Poland to Kharkiv in northeast Ukraine bordering Russia. The state energy company Ukrenergo reported emergency power outages in six regions. It often shuts down production during attacks as a precaution.

Russia's military on Tuesday said it would retaliate against Ukraine after Kyiv attacked Russian regions by firing six U.S.-made ATACMS ballistic missiles, six UK-made Storm Shadow cruise missiles and launching one of the biggest drone attacks to date.

NATO member Poland scrambled fighter jets after overnight Russian missile and drone attacks on Ukraine, Warsaw's military said on Wednesday. Newsweek has reached out to Polish authorities and Russia's Defense Ministry for comment via email.