The Court of Justice of the European Union will set the penalties.

Poland’s government said the move was an “unlawful attack” on the country’s constitutional order and sovereignty. Zbigniew Ziobro, the justice minister, accused the EU of “blackmail of a corrupt nature”.

The country has failed to abide by CJEU instructions to suspend a new body that has the power to discipline judges. The court ruled that the body, introduced as part of the Law and Justice (PiS) government’s reforms since 2017, undermines the “independence and impartiality” of the courts and was incompatible with EU law.

Poland said last month it would comply, yet it has kept the disciplinary chamber in operation.

Vera Jourova, a vice-president of the European Commission, said: “The disciplinary chamber is continuing some of its activities against judges, even though all those activities were supposed to be fully suspended.”

The CJEU will determine the penalties before the end of the year.

Konrad Szymanski, Poland’s EU minister, said that disputes came with “a political cost for the EU in Poland”. He said Poland was owed money by the EU as a matter of “international agreements” and law.