Thousands of Poles have joined rallies in Warsaw and other cities to show support for a judge suspended for having questioned the government's controversial court reforms.

Demonstrators in front of the justice ministry in the capital carried EU flags and signs saying, "Honour and glory to unbreakable judges", and "Independent courts are every citizen's right".

"Those in power are doing everything to destroy the rule of law and judicial independence," said Judge Krystian Markiewicz, president of the Iustitia association of Polish judges that organised the protest.

"We want to show that we'll leave no judge high and dry," he told the TVN24 commercial news channel.

Poland's right-wing Law and Justice (PiS) party has been the target of criticism both at home and from the European Union since it introduced sweeping judicial reforms after coming to power in late 2015.

The government insists the changes are needed to tackle corruption and overhaul a judicial system still haunted by the communist era.

But the EU has accused the PiS-led government of threatening to undermine principles such as the rule of law and judicial independence.

The right-wing Law and Justice party introduced judicial reforms after the 2015 electoral win

The rallies were in support of Judge Pawel Juszczyszyn, who in the process of examining an appeal in the eastern city of Olsztyn questioned the impartiality of the judge who delivered the original verdict.

That judge was nominated by the new PiS-created National Judicial Council, which lacks independence according to opponents.

On Thursday, a disciplinary case was launched against Mr Juszczyszyn and on Friday he was suspended.

"I call on my fellow judges: don't let yourselves be intimidated, be independent and brave," Mr Juszczyszyn told protesters in Warsaw.

Poles also rallied in other cities including Krakow, Poznan, Szczecin and Wroclaw.