Rotterdam’s mayor has defended the city’s police force after officers opened fire on protesters when riots erupted during a demonstration against fresh restrictions to stem the spread of Covid-19, injuring at least seven people.

More than 20 people were arrested on Friday night as protesters threw rocks at police and set fires in the Dutch city to show their discontent over new measures that will curb access to venues, including restaurants and shops for the unvaccinated, and are set to be in place for at least three weeks.

Ahmed Aboutaleb, the mayor of Rotterdam, blamed protesters for an “an orgy of violence” as he justified the use of force to contain the situation.

“Police were forced to draw their weapons and even fire direct shots,” Aboutaleb told reporters, adding that some police officers were injured and that more arrests were expected after an analysis of security footage.

Ferd Grapperhaus, Dutch justice minister, said that the “extreme violence” against police and fire fighters in the port city was repulsive.

“The right to protest is very important in our society but what we saw last night was simply criminal behaviour,” he added.

Police said that the protests had turned into riots. “Fires have been set in several places. Fireworks were set off and police fired several warning shots”. 

Local authorities said police units from around the Netherlands had been deployed to Rotterdam to restore order as they issued an emergency declaration that banned people from gatherings in the area where the riots took place.

Following the violent scenes in Rotterdam, organisers of a planned protest in Amsterdam on Saturday said they had cancelled the event. But another protest in the southern city of Breda against current measures to curb the spread of the virus, which include the 8pm closure of bars, restaurants and clubs, was set to go ahead.

This is not the first time there have been violent outbreaks in the Netherlands over coronavirus restrictions. In January rioters and police clashed on the streets of Rotterdam after a curfew came into force.

Many European countries are reviving draconian restrictions, to fight the spread of the coronavirus as it continues to threatens to overwhelm health systems despite vaccination campaigns.

Thousands of protesters gathered in Vienna after the Austrian government announced a full lockdown and a vaccine mandate. Germany ruled out a lockdown but Jens Spahn, the health minister, spoke of “a national emergency that requires a combined national effort”.

In central Vienna, a mostly peaceful demonstration of tens of thousands of protesters turned violent by mid-afternoon, with a small group of protesters throwing objects at police, such as beer cans and bottles, and detonating smoke bombs and fireworks.

Police were involved in scuffles with protesters in the Heldenplatz — outside the former royal palace — where demonstrators had converged after marching around Vienna’s central Ring boulevard.

In one incident a demonstrator attempted to snatch a firearm from a police holster.

Authorities estimated around 35,000 people had turned up to the protests — the largest so far during the pandemic. Austria’s rightwing populist Freedom Party said the turnout was closer to 100,000.

Ten arrests had been made by mid-afternoon, police said. A number of offences were also registered under the Austrian Verbotsgesetz, the law which bans Nazi symbols and propaganda. Several protesters were seen wearing yellow Jewish stars — apparently intending to draw a comparison between the requirement for an injection and the horrors of Nazism.

The convicted neo-Nazi Gottfried Küssel was spotted at the demonstration, as well as the leader of Austria’s extreme rightwing identitarian movement Martin Sellner.

The majority of demonstrators were from the political mainstream.

The outpouring of anger, which brought people of all ages from across the country to the capital, has been triggered by the sweeping new measures to fight the pandemic announced by Austria’s government on Friday.

Under them, Austria is set to become the first country in Europe — and only the fifth in the world — to make vaccination mandatory for all adults.

A blanket three-week lockdown for the country, beginning on Monday, was also announced.

Austria’s rolling seven-day average of daily new infections per 100,000 residents is more than triple the EU-wide average, according to data from Johns Hopkins University.