The European Union is not a cash cow to be milked by Poland, the vice-president of the European Commission Jyrki Katainen told reporters in Warsaw on Wednesday (1 May).

"The EU is not just a money machine, a cow that you can milk. We are expecting a more substantial contribution from Poland for the future of Europe," he was quoted as saying by Reuters news agency.

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The criticism comes amid a wider dispute over Poland's backsliding on the rule of law after having adopted laws that erode judicial independence.

Poland joined the European Union 2004 and has since received over €100bn in EU funding, more than any other EU member state.

But its right-wing government led by the nationalist Law and Justice (PiS) maintains a shaky relation with the European Union.

The country risks losing its voting rights at the EU level under the so-called article 7 procedure, launched in 2017, over the rule of law issues.

The threat appears to have done little to dissuade Warsaw from changing paths despite popular protests against the laws.

"The current situation is not good because we have had Article 7 procedure in Poland but unfortunately nothing has happened," said Katainen.

Some EU states have since grown frustrated with Poland.

In March, Belgium and German proposed shoring up monitoring of domestic rule of laws with a peer review system to ensure they comply with democratic values.

Meanwhile, the commission is now demanding Poland contribute more towards the EU cohesion fund given UK's projected departure from the European Union.

It also wants Poland to join the euro. But PiS has refused, stating that the country first needs to be on par with Germany, the bloc's largest economy.

"Poland is a fiscally prudent country and it would benefit a lot from eurozone membership," said Katainen.

Katainen was in Poland to help mark its membership, along with nine other countries, of the European Union 15 years ago.

"The most important thing is that EU is based on common values. Rule of law, democracy and human rights," he said in a tweet, following the event.