Kövesi slams Warsaw for refusing to cooperate

She issued her warning in a letter to the European Commission summarised by her office, which said that whenever the European prosecutor was unable to get evidence from Poland, its "ability to counter criminality affecting the Union budget is systematically hindered."

Warsaw says it's not delaying but instead in the process of modifying its criminal law to recognise the Luxembourg-based EU agency as a competent authority.

But the European prosecutor is losing patience in a standoff taking place against a backdrop of tensions between Brussels and Warsaw over the rule of law.

"By saying that they first need to amend the Polish criminal procedure code before they are recognizing EPPO as a competent authority, they are challenging the supremacy of EU law," the European prosecutor's office told EUobserver.

The European prosecutor's office began life only in June last year, with 22 of the 27 member states participating so far.

Poland is one of five member states that have so far not joined the organisation.

Sweden, however, is expected to join in 2022 while Denmark and Ireland have opt-outs for justice matters. That leaves Poland and Hungary as the holdouts.

Kövesi's office said cooperation between the EPPO and the Polish judicial authorities still has to rely on existing tools for judicial cooperation and mutual recognition.

The European prosecutor office had asked Polish authorities for support in 23 anti-fraud investigations involving Poland, and Warsaw had so far rejected the requests.

But the European prosecutor said Polish authorities had obligations to protect the EU budget despite not being an EPPO participating member state.