Strasbourg - Poland's prime minister has reacted furiously after the European Parliament voted to start an EU sanctions procedure over Warsaw's controversial judicial reforms.

MEPs overwhelmingly backed a resolution that warns the reforms by Poland's right-wing government present a "clear risk of a serious breach" of European values, including the rule of law.

The vote, which passed by 438 votes to 152 with 71 abstentions, also means the parliament will formally request the EU to trigger a procedure that could eventually suspend Warsaw's voting rights in the bloc.

Poland's right-wing government has been at loggerheads with the EU for months over proposed changes to the Polish court system that Brussels views as a threat to the union's underpinning democratic values.

- 'Xenophobic and fascist' -

Right-wing Polish lawmakers walked out of the vote in Strasbourg, France, and Polish Prime Minister Beata Szydlo launched a furious attack on the move.

"At the European summit on Friday I will give my views on the scandalous events in the European Parliament," Szydlo said late Wednesday on Twitter, referring to a meeting of EU leaders in Sweden this week.

She condemned opposition Polish MEPs for "defaming" the country by staying in parliament for the vote.

The proposals to overhaul Poland's judicial system have led to mass street protests and prompted Polish freedom icon Lech Walesa to express concern about his country's fate in Europe.

How Article Seven of the European Union works

The changes would reinforce political control over Poland's Supreme Court and allow parliament to choose members of a body designed to protect the independence of the courts.

Szydlo's government says the reforms are needed to root out corruption and purge a judiciary it believes is stacked in favour of supporters of former prime minister Donald Tusk, who is now president of the European Council.

The EU has said the Polish reforms pose a "systemic threat" to the rule of law, with Brussels having warned it could trigger Article Seven of the EU's treaties -- the so-called "nuclear option" that freezes voting rights.

"If the risk persists and the Polish authorities refuse to comply with the EU recommendations, the procedure might lead to the suspension of Poland's voting rights," the European Parliament said in statement on Wednesday.

MEPs also called on the government to condemn the "xenophobic and fascist march" organised by far-right groups which drew around 60,000 people in Warsaw on Saturday, where some demonstrators chanted "Pure Poland, white Poland".

European Commission Vice President Frans Timmermans, who has been leading the EU's response on the judicial reforms, told MEPs there had been little progress with Warsaw despite months of talks.

"We have now sent four letters to the Polish authorities to seek a meeting," but received no response, Timmermans said.

A growing east-west split in the EU has seen Brussels take on both Poland and Hungary over a series of issues including the countries' refusal to take in migrants and Warsaw's large-scale logging in a primeval forest.

The only other time the European Parliament has requested the activation of Article Seven was against Hungary in 2017.

Concern over the growing split has prompted Germany to lead a push to make the EU funds that eastern countries have relied on dependent on complying with democratic standards.

EU ministers met in Brussels on Wednesday to discuss the proposal, but EU Regional Policy Commissioner Corina Cretu said the move risked unfairly penalising people living in those countries.

"Why punish citizens, not to give them schools and hospitals and roads, because of the behaviour of a country?" said Cretu, who is from the former Soviet-bloc state of Romania.

By Arnaud Bouvier