STRASBOURG, France (Reuters) - Five of the main political groups in the European Parliament urged the European Commission on Thursday to open infringement proceedings against Poland and to take it to the European Court of Justice to stop planned judicial reforms.

European Commission First Vice-President Frans Timmermans attends a debate on the Future of Europe at the European Parliament in Strasbourg, France, June 13, 2018. REUTERS/Vincent Kessler

The call by the leaders of the center-right European People’s Party, the centrist Liberals, the Socialists and Democrats, the Greens and the Unified European Left follows criticism from Commission vice-president Frans Timmermans, who has accused Warsaw of breaking EU obligations.

Frustration with Poland is focused on plans by the governing right-wing Law and Justice party (PiS) to change the law on judicial appointments, a move that may force up to 40 percent of judges, including on the Supreme Court, to retire from July 3.

“In reforming the judiciary you still need to respect the independence of the judiciary,” Timmermans said.

“If you believe that through putting the judiciary under political control you can make it a better judiciary you are wrong and you are violating your own obligations under European treaties,” he said. “That is the core element of our discussion with the Polish government.”

In a joint letter, the five main European Parliament groups called on European Commission President Jean-Claude Juncker to begin what is known as infringement proceedings against Warsaw, effectively a form of sanction against an EU member state.

They also urged Juncker to refer the Polish law to the European Court of Justice with the aim of “putting a stop to this damaging reform as soon as possible”.

Only the far-right and the group of European Conservatives and Reformists, where the PiS deputies from Poland sit, did not sign the letter.

Many senior political figures in Poland, including Nobel Peace Prize winner and former leader of the Solidarity movement Lech Walesa, have appealed to the Commission to ask the European Court of Justice, the EU’s highest court, to issue an injunction against Warsaw’s reform of the Supreme Court.

“The forced retirement of these Supreme Court judges would constitute an irreversible violation of the rule of law. The Commission is at present examining this issue,” Timmermans said.