European Council President Donald Tusk, a former prime minister of Poland, has been accused by the Polish government of “attacking Poland”.

“Today, by using his position to attack the Polish government, he is attacking Poland,” Prime Minister Beata Szydlo tweeted.

Tusk had linked her government to a “Kremlin plan”, without giving further explanation.

As reported by the BBC, the two leaders have long been rivals.

Szydlo’s Law and Justice Party (PiS) is in dispute with the European Commission on several fronts: its refusal to accept refugees under an EU relocation scheme; its encouragement of logging in an ancient forest; and its refashioning of Poland’s media and judiciary. The commission accuses PiS of jeopardising EU rule of law values.

In a tweet in Polish on November 19, Tusk wrote: “Alarm! Severe dispute with Ukraine, isolation within the European Union, departure from the rule of law and judicial independence, attack on the nongovernmental sector and free media. Is this a Law and Justice strategy or a Kremlin plan? Too similar to sleep peacefully.”

Tusk’s reference to the Kremlin appeared to link PiS to alleged Russian interference in EU countries and Ukraine.

Poland’s Foreign Minister Witold Waszczykowski also reacted angrily to Tusk’s tweet, calling it “a desperate scream of frustration”.

He said Tusk “has been unable to carve out an active role in European politics for himself, so he is trying to plunge back into Polish politics”.