A recent march commemorating the 100 year anniversary of the country's independence, that took place in Poland's capital on November 11 took on an ultra-nationalist air when protesters started to set the EU flag on fire, chanting "down with the EU." Over 250,000 people reportedly gathered in the streets to participate in the march.
The All-Polish Youth organisation, which espouses ultra-nationalist and fascist doctrines, posted a photo of the burning EU flag on Twitter.
"The commandant of the metropolitan police is offering a reward of five thousand zlotys ($1,400) to those who help find those who did it," the Warsaw police said in a statement.
The incident has already been criticized by the Centre for Monitoring Racist and Xenophobic Behaviour.
According to the head of Morawiecki's chancellery, Michal Dworczyk, a few incidents have taken place during the march, yet they were considered "minimal."
"A dozen or so irresponsible people cannot destroy a great national holiday," he said.
READ MORE: Nationalists March in Warsaw on 100th Anniversary of Polish Independence (VIDEO)
Two counter-manifestations took place at the Independence Day march in Wroclaw on Sunday.
Later in the day, the police chief stated that three people, including a police officer, were wounded in Poland during the march.
"They threw different things. Two citizens got cut wounds… A police officer was seriously injured in the eye," Szymczyk said at a press conference in Warsaw.
According to the police chief, the local authorities ignored police requests to ban the demonstration organized by a potentially dangerous group. Police cordoned off the participants of two demonstrations, but they still tried to start a scuffle. Szymczyk added that the police were working on identifying the perpetrators.
The EU has recently criticized Poland's judiciary reforms, in particular, a new law that lowers the retirement age for Supreme Court judges to 65. According to Brussels, such reforms may threaten the rule of law in the country.