Far-right protesters clash with police during their annual march, which coincides with Poland's national Independence Day in Warsaw on November 11, 2013. Janek Skarzynski/AFP/Getty Images

Groups of masked Polish youths threw firecrackers and set fire to cars after a march through the center of Warsaw turned violent Monday, the third year in a row the annual day to commemorate Poland's national independence broke down into running battles between rioters and riot police.

The violence, which came on the sidelines of a larger national holiday, underscored the ongoing fault lines in Polish society, where radical right-wing groups have been able to gain some political traction in the aftermath of economic recession while claiming to defend “Polishness” from an array of purportedly foreign threats, including immigration, secularism and European integration.

Their growing profile in Poland mirrors the rise of the far-right elsewhere in Europe. The pain of the economic slowdown around the continent, coupled with local factors, has boosted support for nationalists and anti-immigrant and anti-minority sentiment in countries from Greece to Hungary to France.

In Poland, non-governmental watchdogs say incidents of racially-motivated violence are increasing, while youths shouting far-right slogans have gate-crashed university lecture halls where liberal academics have been speaking.

Several thousand right-wing protesters began their march peacefully Monday – watched by their own stewards in orange vests and with a police helicopter circling above. But violence started when a few dozen youths with covered faces broke off from the procession into a side street and started attacking a building where left-wing radicals had occupied a squat.

Riot police moved in and came under attack from youths throwing firecrackers and stones. As the rioters dispersed, several cars were set on fire.

Polish Prime Minister Donald Tusk said what should have been a holiday had been ruined by acts of aggression and violence. "What happened is unacceptable," he said.

Before the violence broke out at Monday's march, demonstrators chanted: "God, honor, fatherland!" and waved the red-and-white national flag.

"I believe that Polishness is under threat," said one marcher, Grzegorz, who said he was 30. "The Polish government is incompetent and a threat to Polishness."

Another protester, who gave his name as Mateusz, said he had come to "manifest my patriotism."

Police spokesman Mariusz Sokolowski said officers had used rubber bullets, truncheons and pepper spray against the rioters. Several people were arrested. Five officers were taken to hospital, local media reported.

The main target of the rioters appeared to have been any symbol of left-wing, liberal views.

Later, the rioters headed to Zbawiciela Square, one of the most bohemian areas of central Warsaw, where students usually hang out in trendy pavement cafes.

An arch across the middle of the square, decorated in rainbow colors with artificial flowers, had become a symbol of tolerance and diversity. By Monday evening, after the rioters had passed through and set it on fire, all that was left of the arch was a charred, steel skeleton.

Al Jazeera and Reuters