In the northern city of Turin, some demonstrators broke off from a peaceful protest, smashing store windows on an elegant shopping street, setting smoke bombs and hurling bottles at police in a main city square where the Piedmont regional government is headquartered, RAI state TV said.

Police fired tear gas to clear the protesters in Piazza del Castello.

In that same square, hours earlier, about 300 taxis peacefully lined up in neat rows to draw attention to their economic losses from the implosion of tourism and disappearance of workers from the city centre as they do their jobs remotely during the pandemic.

Triggering the violence in Turin were a group of "ultras," as violent soccer fans are known, the LaPresse news agency said. It said five of the protesters were detained by authorities.

In Italy's business capital, Milan, police used tear gas to scatter protesters on Monday night, and an Associated Press journalist saw at least two people detained.

The protests began shortly after the national government's order took effect requiring bars, cafes and restaurants to close their doors at 6pm for the next 30 days as Italy tries to rein the resurgence of coronavirus infections in recent weeks.

Since most Italians don't dine out before 7.30pm at the earliest, the decree effectively wiped out most of the restaurants' already reduced revenue in the pandemic, although takeaway and delivery can continue until midnight.

The crackdown was announced on Sunday, a day after Italy registered more than a half million confirmed coronavirus cases since the pandemic's outbreak.

Smaller cities, including Catania in Sicily, and towns also saw protests on Monday.

In Cremona, a town in northern Lombardy, restaurant owners turned out in front of the local interior ministry's office.

After banging pots and bans, they left them piled up in the street to highlight their economic woes worsened by the latest early-shutdown decree, the ANSA news agency said.

Australian Associated Press