A woman reads a menu as she sits at a restaurant's terrace in downtown Rome.

Italy's Prime Minister Giuseppe Conte tightened nationwide coronavirus restrictions Sunday after the country recorded a record number of new cases, despite opposition from regional heads and street protests.

Cinemas, theatres, gyms and swimming pools must all close under the new rules, which come into force on Monday and run until November 24. Restaurants and bars will stop serving at 6:00 pm, Conte's office said.

Italy, which was the first European country to be hit hard by the pandemic and impose a nationwide lockdown, on Saturday registered nearly 20,000 new cases over 24 hours.

"Semi-lockdown for a month," said the Repubblica daily, noting Conte had done little to appease regional heads who had appealed for much softer measures to save ailing businesses devastated by the lockdown in spring.

Schools and nurseries will remain open, although up to 75 percent of classes for high-schools and universities will move online. People have been urged to avoid using public transport or moving beyond their own communities where possible.

The new measures were introduced just hours after dozens of far-right protesters in Rome clashed with riot police during a demonstration against the region's curfew, setting off fireworks, burning bins and throwing projectiles.

Some 200 masked militants belonging to the neo-fascist group Forza Nuova lead the skirmish in a second night of street protests, after hundreds of demonstrators clashed with officers in Naples further south over their curfew.

'Paying the consequences'

Several regions have imposed overnight curfews in a bid to slow-rising Covid-19 infection numbers. Piedmont in the north and Sicily in the south will follow this week.

But regional leaders had warned that closing businesses would exacerbate social tensions as the country struggles to emerge from its worst post-war recession, sparked by the two-month shudown earlier this year.

Giuseppe Spadafora, deputy president of business lobby Unimpresa, said the "anger could explode in the coming days and weeks, becoming difficult to control".

Conte, however, has been under intense pressure from scientists to do more to curb contagion.

Italy has now registered over 500,000 cases and more than 37,000 deaths, according to health ministry figures.

Over 100 scientists urged the government to act this week after physicist Giorgio Parisi said that without new measures there would be 500 covid deaths a day in Italy by November, at the speed the virus is spreading.