WARSAW, Poland (AP) -- Poland's Prime Minister Donald Tusk said that Russian hackers attacked the websites of parties in his ruling coalition on Friday, two days before a presidential election.

The frontrunner in Sunday's election is a high-ranking member of Tusk's Civic Platform party, Warsaw Mayor Rafa? Trzaskowski.

"Two days before the elections, a group of Russian hackers operating on Telegram attacked the websites of the Civic Platform," Tusk wrote on X on Friday afternoon.

Tusk said that the websites of other parties in his governing coalition, the Left and the Polish People's Party (PSL), were also targeted. "The services are conducting intensive actions in this matter. The attack is ongoing," he said.

Polish authorities were also investigating paid political advertisements on Facebook that a Polish state research institute, NASK, identified as possible electoral interference. NASK is the Polish acronym for National Research and Academic Computer Network.

The institute said that it reported the misinformation to Meta, which owns Facebook, and that the ads were removed.

"Ad accounts involved in the campaign have spent more on political content than any election committee in the past seven days," NASK said Wednesday. "The actions were intended to ostensibly support one of the candidates and discredit others."

Already in late 2024, Polish authorities had reported up to 1,000 Russian and Belarusian cyberattacks a day targeting government institutions and agencies, and have linked them to the country's support for neighboring Ukraine in its three-year war against Russia's invasion.