The Polish government has offered no measures to address "grave concerns" that it infringes on the rule of law, the deputy head of the European Union's executive said, adding he would seek fresh reaction from Brussels and all the bloc's states.

The euroskeptic, nationalist-minded Law and Justice (PiS) party has been on a collision course with the European Commission and many EU states since taking power in late 2015.

It has moved to put the judiciary and state media under more direct political control and clashed with the bloc over issues from migration to large-scale logging of an ancient forest.

Frans Timmermans, the deputy head of the European Commission who has led for more than a year a case against PiS for undermining democratic principles in Poland, on Thursday told European lawmakers that Warsaw remained adamant in its latest exchanges with Brussels.

At stake is the so-called Article 7 procedure the bloc could launch against Poland, which could theoretically lead to a maximum sanction of stripping Warsaw of voting rights in the EU. That seems way off as Warsaw would most certainly be shielded by regional ally Hungary from that punishment.

But even launching the Article 7 scheme — so far unprecedented — would deal a blow to Warsaw as it would become the first country ever to be taken to task by the rest of the EU over democratic values in such a direct way.

"The Polish reply does not announce any concrete measures to address the issues raised by the commission," Timmermans told a parliamentary hearing of the formal letter he received from Warsaw in response to a third set of recommendations issued by Brussels to remedy the situation.

"We remain open to dialogue, we remain open to finding constructive solutions. But, at the same time, we must discuss internally in the commission, and with member states ... and with the European Parliament the new situation that has now arisen."

Merkel, Macron express concern

German Chancellor Angela Merkel, French President Emmanuel Macron and many other Western EU leaders have thrown their weight behind the European Commission in the dispute with Poland, the largest eastern member of the bloc.

Warsaw has not changed its tack despite street protests in Poland, alarm sounded by the opposition and rights groups or growing ostracism in the EU.

Poland says it has a strong public mandate to carry out reforms, the latest ones introducing changes to the judiciary, including allowing the justice minister to hire and fire judges more easily.

People attend a protest in Szczecin, Poland on July 27, one of several that has taken place as the Law and Justice Party has stacked the courts with favourable candidates and stifled the country's media. (Agencja Gazeta/Cezary Aszkielowicz via Reuters)

Warsaw has said its overhaul of the judiciary is in line with European standards and that the European Commission's concerns about rule of law in the country of 38 million people are groundless.

"The commission does not contest the right of the Polish government to introduce judicial reform," Timmermans said. "But we do maintain that judicial reform must respect the rule of law as one of the fundamental values which all member states signed up to when they joined the EU."

Another possible consequence Poland faces in its running battles with the EU is that the bloc will eventually siphon away the generous EU development funds from Warsaw for violating key principles on which the bloc is built.