European Commission Vice President Vera Jourova voiced concern over the Polish government's "smear campaign" against judges during a visit to Warsaw Tuesday to discuss the rule of law with authorities.

Last week the country's Prime Minister Mateusz Morawiecki accused the Supreme Court of "destabilising the legal order".

The court had ruled that judges chosen by new government-backed institutions had no authority to issue verdicts because they were not free from outside influence.

That decision was the latest development in a long-running controversy over judicial reforms introduced by the ruling Law and Justice (PiS) party since it came to power in 2015.

The right-wing populist PiS argues that the reforms tackle corruption in a judicial system still stuck in the communist era. Critics, who include top European judicial bodies, say the changes undermine the rule of law and threaten democracy.

Already last week the PiS-controlled parliament approved a controversial reform that proposes disciplining judges who question the government's reforms.

Although critics have objected that this would gag dissenting voices, Polish President Andrzej Duda has made it clear he is ready to sign the bill into law.

Last Friday, Jourova asked the European Court of Justice to temporarily suspend the implementation of the legislation so that its judges could review its contents.

"The door for a dialogue with Poland is open... But at the same time I am concerned about the smear campaign against the (Polish) judges," Jourova told reporters after meeting with Poland's Ombudsman Adam Bodnar on Tuesday.

Earlier this month, hundreds of Polish judges were joined by colleagues from several European countries in a march in Warsaw to protest the changes Earlier this month, hundreds of Polish judges were joined by colleagues from several European countries in a march in Warsaw to protest the changes Photo: AFP / JANEK SKARZYNSKI

"I would like to do more to protect the judges against the campaign against them because this is not the atmosphere where I can imagine the judges can do their demanding job," she added.

"I would wish to have a good long-term solution... The campaign against the judges is something very harmful."

Earlier Tuesday Jourova met with the speakers of the lower house of parliament and of the senate. She is also due to hold talks with Justice Minister Zbigniew Ziobro, as well as the presidents of both the Supreme and Constitutional courts.

PiS spokeswoman Anita Czerwinska said Tuesday "we are open to dialogue with the European Commission".

But she denounced what she called Brussel's "double standards" regarding its responses to Poland versus other EU member states.

On Saturday, Poland's foreign ministry summoned the Commission's representative in Warsaw after the European Commission said it was "concerned about the rule of law situation in Poland".

That statement was "unacceptable", said Warsaw.

The European Union has repeatedly expressed concern over the judicial changes.

In 2017, it launched unprecedented proceedings against Poland over "systemic threats" to the rule of law that could see its EU voting rights suspended.

Earlier this month, hundreds of Polish judges were joined by colleagues from several European countries in a march in Warsaw to protest the changes.