Hundreds of protesters in Naples threw projectiles at police and set rubbish bins on fire late Friday during a demonstration against coronavirus restrictions in the southern Italian city.

Calls were issued on social media to challenge a curfew that took effect in the Campania region ahead of the weekend, enacted in response to a spiralling second wave of infections that saw nearly 20,000 new cases detected in the last 24 hours.

A mostly young crowd marched through the streets of the regional capital and chanted as the curfew started at 11 pm, with some lighting smoke bombs.

One carried a makeshift sign that read: "If you close, you pay."

Regional president Vincenzo de Luca had called for stricter confinement measures to contain the virus in Campania, which recorded 2,300 cases over the last day.

"We are on the verge of tragedy, we need a national lockdown," he said.

Prime Minister Giuseppe Conte has so far avoided reimposing the kind of restrictions that saw the entire nation confined to home quarantine for two months earlier this year and precipitated the country's worst post-war recession.

Italy was the first European country to be badly hit by the virus. It has now registered nearly 500,000 cases and 37,000 deaths, according to health ministry figures.