An attempt by Poland to change the retirement age of its judges broke EU law, the bloc's top court ruled Tuesday, intensifying a showdown between Brussels and the conservative

government in Warsaw over democratic standards.

Rules Poland tried to bring in two years ago, setting lower retirement ages and making them different for male and female judges, were "contrary to EU law," the Luxembourg-based European Court of Justice said, siding with the European Commission.

It also took exception to an associated rule giving Poland's justice minister sole discretion to decide whether to extend a judge's service beyond the mandated retirement age.

"The verdict relates to an old situation that does not correspond to current regulations," its foreign ministry said on Twitter, noting that the reform was changed last year to align the retirement ages of male and female judges, and to hand the power of extending a judge's service to a national magistrates' board.

"The Commission should have withdrawn its complaint after the amended law came into force," it said.

- Illiberal populist government -

Poland's ruling Law and Justice party, which is often at loggerheads with the EU institutions, insists judicial reforms are needed to tackle corruption and change a judicial system still carrying some communist-era legacies.

But the European Commission sees their stance as part of a disturbing trend among some eastern member states towards autocratic rule that ditches EU standards of democracy, judicial independence and rule of law.

Poland, the Czech Republic, Hungary and Romania are all being scrutinised to varying degrees over rule of law concerns, with Brussels worried that oligarchs and wealthy political figures are concentrating power.

The right-wing populist Law and Justice party, which took office in late 2015 and won re-election last month, is fiercely conservative, opposing LGBT rights while boosting welfare spending and wooing rural voters.

Its leader Jaroslaw Kaczynski -- widely regarded as Poland's ultimate powerbroker -- said in October his party has a mandate "to continue to change Poland".

It has already carried out controversial moves to monopolise public media as well as implement the judicial reforms.

Its attempted changes to the judges' retirement age introduced in July 2017 called for male judges to step down at 65 and female ones at 60. The previous retirement age was 67 for both sexes.

Judges resisted what they saw as early retirement orders, arguing the government was trying to shift independent magistrates off the bench to replace them with loyalists.

In its ruling, the European Court of Justice said that reform violated EU rules on non-discrimination between genders when it comes to equal pay and pensions.

It dismissed Poland's argument that the changes represented "positive discrimination," saying that "those differences do not offset the disadvantages to which the careers of female public servants are exposed".

The court also decided that the terms under which the justice minister might decide to have a judge stay on were "too vague and unverifiable" and called into question the neutrality of the judges concerned.

- New case -

Even though Warsaw asserts that it now conforms with EU law on the judges' retirement age, it remains in hot water with Brussels.

A month ago, the European Commission took Poland's government to the EU court over another judicial reform: a new disciplinary regime for judges that allegedly threatens their independence.

Poland's Justice Minister Zbigniew Ziobro has called the new case -- the third by the Commission against Warsaw -- a "political act" that "could prove counter-productive".afp