Dutch police said Sunday they had arrested 48 people after a second night of violent riots erupted over the government's coronavirus measures.

Prosecutors meanwhile updated to four the number of people shot when police opened fire during an "orgy of violence" in the port city of Rotterdam on Friday night.

The two nights of unrest in a number of cities came a week after the Dutch government went into a partial lockdown over a surge in cases.

In The Hague on Saturday night, officers in riot gear charged demonstrators who set fire to bicycles and an electric moped piled in the middle of a busy intersection.

"The police were also pelted with heavy fireworks and stones thrown from roofs," police said in a statement, adding that water cannon was used to put out the fire.

"Officers made a total of 19 arrests for, among other things, insult."

Five police officers were injured during the unrest while a rock thrown by rioters smashed the window of a passing ambulance carrying a patient, police said.

Thirteen people were arrested in separate riots in the towns of Stein and Roermond in southern Limburg province after fireworks were thrown at officers, police said.

Police also made 16 arrests during clashes in the "Bible Belt" town of Urk, where vaccination rates are very low due to conservative Protestant beliefs, local media said, quoting police.

 'Going wild'

Municipal workers surveyed the damage in The Hague's working-class Schilderswijk district on Sunday including a security camera toppled by the rioters and a patch of burned road where the pile of bikes was torched.

Local residents blamed the riots on frustrated youths and uncertainty over whether the government will introduce so-called "2G measures" that would let cafes and bars decide whether to turn away the unvaccinated.

"They don't know (if 2G will be introduced) and so they don't know what to do... They think that is the way to make themselves heard," Mustafa Toprak, 31, told AFP.

"It's a bad way to do it, but hey it's the young people who are going wild."

"They are young people and they have had few freedoms because of Covid-19 for almost two years now so yes I understand somehow -- only I can't approve," said Claudia van der Wijngaard, 60.

"No, I don't really see a solution as long as the government continues to work with sanitary measures, I don't see a solution coming and I'm afraid there will be more (riots)."

 'Hit by bullets'

On Friday violence broke out in the port city of Rotterdam after a protest against Covid measures, during which police opened fire and 51 suspects were arrested.

"It now appears that four people have been hit by bullets," the Dutch public prosecutor's office said in a statement, blaming medical confidentiality rules for the delay in getting the correct figure.

Police had previously said three people were wounded by gunshots and were being treated in hospital.

Some of the Rotterdam rioters had links to football hooligans and "groups that often have ties to other forms of organised crime," Justice and Security Minister Ferd Grapperhaus told public broadcaster NPO.

The Netherlands went back into western Europe's first partial lockdown of the winter last Saturday with at least three weeks of curbs under which bars, cafes, restaurants, supermarkets and non-essential shops must shut early.

The government has said it wants to bring in the 2G option -- which would bar unvaccinated people from getting Covid passes for some venues -- after that, but there has been opposition in parliament.

In January the Netherlands suffered its worst riots in decades after the government introduced a coronavirus curfew.