He spoke out when asked by a journalist if Poland's judicial reforms and the re-election of the authoritarian Viktor Orban in Hungary posed threats to the EU.

"I have seen Europe in its different forms. I've come to this country [Poland] when it was still a [communist] dictatorship. I've also come to Hungary when it was still a dictatorship. You [the journalist] are of an age that you have never seen that, and we Europeans have a strong duty to make sure that you will never, and that my children will never, see it back again," he said.

He added that he was "comforted" by the level of pro-EU sentiment in Polish and Hungarian society despite the developments.

"The vast majority of Polish people, as Hungarian people, feel a strong sense of belonging to the European Union and this is what will dictate our common future," he said.

Timmermans went to Warsaw to discuss potential changes to judicial reforms which, critics say, will hand political control of Polish judges to the ruling Law and Justice (PiS) party and which could lead to EU sanctions on Poland.

He went there one day after Orban secured a sweeping victory in Hungary on the back of the kind of illiberal reforms now being put in place by PiS ahead of Polish elections in 2019.

Hungary has vowed to veto any EU sanctions on Poland, with the Polish foreign minister, Jacek Czaputowicz, indicating on Monday that Orban's victory might harden Warsaw's stance.

Czaputowicz said there was room for "manoeuvre" and "compromise" with Timmermans, but he said the "essence of this system [the Polish judicial reforms] cannot be lost, it must start to enter into life."

Hungary-Poland axis

"We are happy that Hungary has decidedly spoken out on our side when it comes to the clash with the European Commission regarding article seven [of the EU treaty, on sanctions]", he added.

He also defended Orban, whose campaign included EU conspiracy theories about a Muslim invasion of Europe, against charges of "populism".

"This is part of our EU. These views are justified. They should be respected and that's our approach to it," Czaputowicz said.

The Polish government has depicted the rule of law dispute as an attempt by EU bureaucrats to infringe on national sovereignty.

Timmermans pushed back against that claim on Monday, saying: "The debate isn't about whether Poland has a right to reform its judicial system. That's not our competence. We want to be sure, that the Polish justice system maintains its independence."

"This is enshrined in the heart of the European Union," he said.

Dialogue

Timmermans and Czaputowicz made nice on the importance of maintaining dialogue, with more high-level meetings afoot, as Polish MPs digest the final details of the judicial bills next week.

"We can see some actions taken by the parliament, we are analysing them very closely and carefully. We haven't seen an end of this process yet," Timmermans said in Warsaw on the risk of an EU sanctions clash.

"We will reveal our assessment once ... we have a clear image. I hope it will be positive," he said.