The rallies on Sunday were held in response to a court ruling that said key EU laws were “incompatible” with the Polish constitution. The ruling raised concerns Poland could follow Britain and leave the EU.
However, the Polish government has denied having such intentions.
Following the court’s decision, protests were held across 100 towns and cities, including the capital, Warsaw.
In one powerful moment, two veterans of the Warsaw uprising took to the stage at the anti-Polexit protest in the capital.
They told a crowd of protesters: “We have always been in Europe.
“No one will get us out of it.
“This is our Europe.”
MEP Nathalie Loiseau took to Twitter to urge people to “listen to those who have lived through a tragic past rather than those who reinvent the past to lead us towards the tragic”.
Poland’s Prime Minister, Mateusz Morawiecki, defended the decision and said his ruling party had no plans for Polexit.
This marks the first time in the history of the 27-strong EU bloc that a leader of a member state had questioned wholesale EU treaties in a constitutional court, the BBC reported.
Mr Morawiecki wanted to prevent Polish judges from using EU law to question the legitimacy of judges following recent changes to the judiciary.
These changes were criticised by the European Commission for undermining judicial independence and increasing political control over courts.
EU Commission chief Ursula von der Leyen said she was “deeply concerned by the ruling”.
She vowed to “uphold the founding principles of the EU’s legal order”.
Poland has increasing been at odds with the EU Commission over issues ranging from LGBTQ+ rights to judicial independence.
The Commission has yet to approve Poland’s €57bn (£50bn) Covid-19 recovery plan.
The EU Covid recovery fund was met with anger as the bloc wants to link the behaviour of member states with access to the funds by means of a “rule of law” mechanism.
This means any country which pursues policies which the EU feels do not uphold its core values will lose access to the vital funds.
Last year, Hungary and Poland blocked the EU budget over the rule of law issue.
Hungarian Prime Minister Viktor Orban said his country’s position on the budget and recovery fund is “rock-solid” and will not seek a compromise on the rule of law issue.