The European Union has become a source of "crisis" for Poland, its foreign minister said Thursday amid a cooling of ties between Brussels and the new rightwing government in Warsaw.

"We know today that more Europe means more crisis in Poland," Witold Waszczykowski said in a statement published on the foreign ministry website.

Around a quarter of a million Poles flooded central Warsaw Saturday, marching to defend their country's place in the European Union and protest against moves by the right-wing government, which they say undermine democracy.

Warsaw city hall said the protest drew some 240,000 people, making it one of the largest demonstrations since the 1989 collapse of communism in Poland.

Hungary and Poland on Wednesday slammed a European Union plan to fine member states that refuse to accept their quota of refugees, with Budapest calling it "blackmail" and Warsaw saying it sounded like an April Fool's joke.

The European Commission has proposed making EU countries pay a "solidarity contribution" of 250,000 ($290,000) euros per refugee they decline to take in as Europe struggles with its worst migration crisis since World War II.

Poland on Thursday discounted as "political" a draft report by European legal experts warning that reforms by the right-wing government put democracy, human rights and the rule of law at risk.

Last month the Venice Commission, a body of the Council of Europe, submitted a draft report to the Law and Justice (PiS) government finding Poland is in "constitutional crisis" after the populist administration's legislative reforms paralyzed the EU member's constitutional court.

NATO member Poland is ready to send four F-16 warplanes to fight the Islamic State group in Syria and Iraq, a senior defense official said Monday.

The move came after NATO signaled last week it was considering joining the U.S.-led coalition fighting the jihadists.

Poland's Prime Minister Beata Szydło said Friday a proposed deal to keep Britain in the European Union was "mostly acceptable" to Warsaw but stressed that Polish workers in the UK should not lose out.

The proposals are "mostly acceptable," she said, after talks with German Chancellor Angela Merkel, but she added that "what is particularly important for us is that... everything must be done to ensure that Poles who are working in Britain are also respected and given guarantees."

All eyes in the sleepy Polish town of Slopnice were fixed on the U.S. presidential race Tuesday as Bernie Sanders, whose father was born there, was in a virtual tie with frontrunner Hillary Clinton for the Democratic party nomination.

"There's quite a bit of excitement in the air here -- we're proud of Senator Sanders and we wish our 'homeboy' even greater success!" mayor Adam Soltys told AFP.

Poland's defense minister said on Thursday that NATO's presence must be boosted in eastern Europe to counter the threat posed by Russia.

For Poland, "strengthening the eastern flank of NATO is a priority," Antoni Macierewicz said during a meeting with his German counterpart Ursula von der Leyen in Berlin.

Hungary's Prime Minister Viktor Orban, a key ally of Warsaw's conservative government, said Friday that Budapest would move to block any EU sanctions on Poland.

"Hungary would never support sanctions against Poland," Orban said in his weekly interview on public radio.

Poland's foreign minister on Tuesday accused Germany of putting Russia's interests above the security of eastern Europe, saying Berlin had neglected to show solidarity with its neighbors.

Retorting sharply to accusations against Warsaw over its refusal to shoulder a bigger share of refugees streaming into Europe, Witold Waszczykowski instead questioned Germany's stance on eastern Europe.