There ⁠are strong reasons to believe a group connected to Russian secret services was behind a December cyberattack on Poland's energy ‍infrastructure, Polish Prime Minister Donald ‍Tusk said on Thursday.

Poland's power system faced its ⁠largest cyberattack in years in the last week of December, its energy ​minister Milosz Motyka said on Tuesday.

Tusk added that because Poland's defense systems worked ‍well the attack did not threaten critical infrastructure ⁠and had practically no negative consequences.

"There are many reasons to believe... that they were prepared by groups directly linked ⁠to the ​Russian services, ⁠I don't want to speculate, but I don't ‍think we have any doubts about the sources ‌of inspiration," Tusk told a press conference.

"I want to say that Poland ⁠defended ​itself against attempts ‍at destabilization, and its infrastructure was never threatened for a ‍moment."