Youths and police clashed for a second day in Milan on Sunday, where mostly black-clad assailants hurled bottles, ransacked stores and destroyed property around the central Duomo plaza.
Police in the northern city have arrested more than 200 people since Saturday, according to Ansa news agency.
The Milan clashes began on Saturday on the sidelines of a sanctioned cost-of-living demonstration.
Similar troubles took place in the northern cities of Bologna and Turin following other protests.
On Sunday, police used tear gas and water cannon to disperse groups in the Milan square, and video images showed young people, many wearing masks, throwing objects at police cars.
A supermarket on a shopping street leading off the Duomo plaza was ransacked, rubbish bins overturned and scooters and bicycles vandalised.
The mayor of Milan, Giuseppe Sala, said that he had witnessed "smashed shop windows, looted stores, and frightened citizens".
"What happened here is what we are seeing in many cities around the world," he told Ansa.
"I’m very worried because it’s a new phenomenon, which also originates from an international scenario and therefore feeds itself."
Prime Minister Giorgia Meloni called for a security meeting on Monday to address the violence, which resembled some scenes of chaos and looting in Paris.
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On Saturday, Meloni called the vandals "thugs who exploit demonstrations to spread chaos, attack those who guarantee security, and hold entire cities hostage".
"To demonstrate is a right. To lay our cities to waste is not," she wrote on X.
