Polish Prime Minister Mateusz Morawiecki has accused the EU of blackmail in a heated debate with European Commission chief Ursula von der Leyen over the rule of law.
The clash in the European Parliament follows a top Polish court ruling that rejected key parts of EU law.
Mrs von der Leyen said she would act to prevent Poland undermining EU values.
In response, Mr Morawiecki rejected “the language of threats” and accused the EU of overstepping its powers.
Poles overwhelmingly support being part of the EU, opinion polls suggest, but Poland’s right-wing nationalist government has increasingly been at odds with the union on issues ranging from LGBT rights to judicial independence.
The latest row has come to a head over an unprecedented and controversial ruling by Poland’s Constitutional Tribunal that in effect rejects the core principle that EU law has primacy over national legislation.
The case, brought by the Polish prime minister, was the first time that an EU member state’s leader had questioned EU treaties in a national constitutional court.
‘A direct challenge’
On Tuesday, Mrs von der Leyen told the European Parliament that the European Commission – the EU’s executive – was “carefully assessing this judgement”.
She said the situation had to be resolved, but she was adamant: “This ruling calls into question the foundations of the European Union. It is a direct challenge to the unity of the European legal order.”
Vowing to take action, Mrs von der Leyen set out three ways the European Commission could respond to the Polish court judgement.
The options, she said, were legally challenging the court ruling, withholding EU funds and suspending some of Poland’s rights as a member state.
The European Commission is yet to approve €57bn (£48bn; $66bn) of Covid-19 recovery funds earmarked for Poland, and may not do so until the dispute is settled.
In a speech that ran over his allotted time, Mr Morawiecki said Poland was “being attacked” by EU leaders and it was “unacceptable to talk about financial penalties”.
“Blackmail must not be a method of policy,” said Mr Morawiecki of Poland’s ruling conservative-nationalist Law and Justice party.