Dozens of protesters attacked police in Warsaw during Poland’s independence day celebrations on Friday.
A spokesman for Warsaw police said 100 people were arrested, adding that many of them were anarchists from Germany.
The demonstration by far-right groups was countered by a peaceful march of some 300 left-wing protesters, who held anti-capitalist banners and chanted slogans.
The violence happened despite an earlier call for calm by President Bronislaw Komorowski.
“Let’s not tell people how to love Poland, let’s not celebrate independence day by fighting, let’s celebrate it together,” he said in a speech.
November 11, 2011 marks the 93rd anniversary since Poland regained its independence after 123 years of foreign rule by Russia, Austria and Prussia.