Poland's government needs to do more to preserve judicial independence and avoid "undermining public confidence in it," the Council of Europe's Commissioner for Human Rights said in a report published on Friday.
Since taking office in 2015, Poland's eurosceptic Law and Justice (PiS) party has carried out judicial reforms that European Union authorities say threaten the rule of law.
The party's blend of social spending and nationalist rhetoric remains popular, however, and it is widely expected to win a national election due later this year.
In her report, commissioner Dunja Mijatovic was broadly critical of the government's handling of judicial reform and added that the credibility of the Constitutional Tribunal, the guardian of the constitution, had been seriously compromised.
"Improving accountability or efficiency of the justice system may not be pursued at the expense of judicial independence," she said in a press release announcing the report.
"Members of the executive and the legislature have a duty to uphold the independence of the judiciary and to avoid undermining public confidence in it," she said.
In a comment on the report, the government dismissed her criticisms and said its judicial overhaul, which includes changes modifying the way in which judges are appointed, were conducted lawfully.
The government said all judges in the Constitutional Tribunal were appointed legally. "The Tribunal under the current President carries out its duties in line with the Constitution and the statutes," the government said.
PiS justifies its reforms by saying the efficiency of courts needed to be improved and the changes will root out the lasting remains of communism, which fell in Poland 30 years ago.
Some of the changes to the judiciary PiS has made have been rolled back in the wake of EU protests, including a law forcing Supreme Court judges into early retirement.
But Mijatovic said more needed to be done, criticizing the fusing of the functions of the justice minister and prosecutor-general and demanding the separation of the positions. She also expressed surprise at the dismissal of court presidents and vice-presidents as well as prosecutors across Poland.
In 2016 PiS appointed a new head of the Constitutional Tribunal, Julia Przylebska, a friend of ruling party president Jaroslaw Kaczynski. On Thursday, Przylebska ruled in favour of the government by deciding that a printer in Lodz, central Poland, was right to refuse printing LGBT posters.
Activists have said that this ruling opens the door to discrimination against people not only for their sexual preferences, but also over their race and political beliefs.
LGBT rights have become a hot-button issue in Poland ahead of an election scheduled for October or November, with PiS depicting campaigners as a threat to traditional Polish values.
Mijatovic's report also touched on women's rights in Poland, including securing access to legal abortions.
Termination of pregnancy is legal in Poland in case of rape, when the woman's life or health are in danger, or if the fetus is irreparably damaged, but the media and NGOs have reported that women have difficulties obtaining abortions in such cases.