RMF24 reported the information.The concert took place on August 9. Afterward, police launched an investigation and detained 109 people for disturbing public order. Among the incidents was the display of a red-and-black flag, which is banned in Poland.The flag in question is associated with the Ukrainian Insurgent Army (UPA) and the Organization of Ukrainian Nationalists (OUN), movements that fought for Ukrainian independence during and after World War II. While many Ukrainians view the banner as a symbol of resistance against Soviet oppression, in Poland the flag is associated with the massacre of ethnic Poles during World War II."Proceedings to remove 63 people from the country have been initiated. They will have to leave Poland either voluntarily or by force," Tusk said.According to him, the event saw numerous offenses, acts of aggression, and provocations that shocked Polish society. At the same time, the Prime Minister stressed that Poland must not allow anti-Ukrainian sentiments to grow.Tusk also called on the Ukrainian authorities to ensure no one engages in anti-Polish gestures and for both countries to resist Russian provocations."We cannot allow a wave of hatred between Ukrainians and Poles, or Poles and Ukrainians, to break out. It would be a historical crime and incredible stupidity if we let ourselves be divided now," he stressed.The Polish Sejm recently approved a new state date — the National Day of Remembrance of Poles "victims of the genocide committed by the OUN and UPA in the eastern lands of the Second Polish Republic," to be marked on July 11.The Ministry of Foreign Affairs of Ukraine, in turn, said the Polish Sejm’s decision to designate July 11 as the Day of Remembrance of the victims of the "genocide committed by the OUN and UPA" goes against the spirit of good-neighborly relations between Ukraine and Poland.Recently, a monument to the victims of the Volyn tragedy was vandalized in Poland.At a concert by Belarusian rapper Max Korzh in Poland, the red-and-black flag of the UPA was raised. Polish Sejm deputy Dariusz Matecki called it "a symbol of criminals and executioners of ancestors."