Poland's prime minister demanded explanations on Tuesday about accusations that a deputy minister sought to discredit judges critical of the government's judicial reforms by planting media rumours about their private lives. Deputy justice minister Łukasz Piebiak announced his resignation on Tuesday afternoon, stating that he didn't want 4 hard years of hard work over Polish judiciary reforms to be affected. He added that he intends to fight for his good name.

"With a sense of responsibility for the success of the reforms, to which I have devoted 4 years of hard work, I file my resignation as the undersecretary of state, at the hands of the Minister of Justice," Piebiak announced on Tuesday.

The prosecutor's office has launched a preliminary inquiry in response to the notification about possible misconduct by deputy justice minister Łukasz Piebiak. The Democratic Left Alliance party has notified the prosecutor, saying that Piebiak may have been illegally processing personal data.

It was the latest in a series of scandals to hit Poland's ruling nationalists - who have come under European Union fire over moves to increase political controls over the judiciary - ahead of elections in October.

The Onet.pl website reported late on Monday that Deputy Justice Minister Łukasz Piebiak was behind a campaign to blackball critical judges including Krystian Markiewicz, a prominent critic of the ruling Law and Justice (PiS) party and head of the judicial association Iustitia.

It published alleged transcripts of conversations between Piebiak and a woman named as Emilia in which they weighed plans to anonymously send material with rumours about Markiewicz's private life to regional branches of Iustitia and to his home.

Emilia, whose surname was not given, acted as an intermediary between the ministry of justice and pro-government media, and also posted material online intended to compromise certain judges, according to Onet.pl.

Onet.pl's report provoked an outcry from the centrist opposition and prompted Prime Minister Mateusz Morawiecki to demand explanations.

"We definitely need to listen to both sides and we will see what the explanation will be and then make the right decisions," Morawiecki told a televised news conference during an election campaign rally.

Markiewicz told private broadcaster TVN 24: "We are dealing with systematic actions taken against judges, against the rule of law in Poland. If such an attack can be made against judges and professors, it means it can be made against everyone."

The Justice Ministry did not immediately respond to Reuters requests for comment. Contacted by Onet.pl, Piebiak said he knew Emilia only "from Twitter" and declined further comment.

"Scandalous situation"

Poland's right-wing Law and Justice (PiS) party has pushed through a range of reforms since taking power in 2015 that the European Commission and rights groups say jeopardise the rule of law by politicising judicial appointments.

The PiS has argued the changes were needed to improve the efficiency of the courts and rid Poland of residues of Communist rule, which ended three decades ago.

Opposition politicians accused the government on Tuesday of using state structures to discredit critics and demanded the dismissal of both Piebiak and Justice Minister and Prosecutor General Zbigniew Ziobro.

"Mr Ziobro, according to the media reports, knew perfectly well about this scandalous situation of baiting independent judges, what's more, he accepted it," opposition lawmaker Pawel Olszewski told a news conference.

Onet.pl said Piebiak was supposed to inform an unidentified "boss" about the effects of the posted rumours.

"This is dangerous for the state, for democratic order... especially because it affects judges and it is paid for with public money," said Anna Materska-Sosnowska, a political scientist at Warsaw University.

Earlier this month, Poland's parliament speaker resigned after it was revealed that he used government aircraft for private trips, a move that suggested the PiS was keen to defuse bad publicity that could affect their re-election bid.

Despite scandals, the PiS looks set to win the October 13 parliamentary vote, regularly polling over 40%. The main opposition Civic Coalition is below 30% in most polls.