media captionDutch police have described it as the worst unrest in four decades

Protesters defying a curfew in the Netherlands have again clashed with riot police, after a weekend of unrest.

More than 150 people were arrested in several cities. In Rotterdam, the police fired warning shots and tear gas, after an emergency order issued by the mayor failed to move demonstrators.

Unrest started over the weekend as protesters kicked back against newly imposed coronavirus restrictions.

Prime Minister Mark Rutte has condemned what he called “criminal violence”.

The Netherlands has had nearly one million confirmed Covid cases since the start of the outbreak, with more than 13,500 deaths, according to Johns Hopkins University in the US, which is tracking the pandemic.

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image captionSeveral cities have vowed to introduce emergency measures in an effort to prevent more disturbances

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image captionThe Dutch prime minister has condemned the violence

There were further violent scenes in several cities across the country on Monday night. Riot police clashed with protesters in Amsterdam as well as Rotterdam, Amersfoort and Geleen. Police in Rotterdam said a number of officers were hurt.

Fires were lit on the streets of The Hague, where police on bicycles attempted to move small clusters of men who threw rocks and fireworks, the BBC’s Anna Holligan reports from the city. There were also reports of looting in a supermarket in

There was violence in the southern city of Den Bosch, where rioters set off fireworks, broke windows, looted a supermarket and overturned cars.

A woman living near the train station told Dutch radio that masked youths had left a trail of destruction in the city centre. “I saw windows smashed and fireworks going off. Really crazy, just like a war zone,” the woman said. Roads into the city were closed to stop people joining the rioters.

A number of arrests were made in Amsterdam and the mayor appealed to parents to keep young people indoors.

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image captionThere have been protests in a number of cities against coronavirus restrictions and a curfew imposed by the Dutch government

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image captionSome of the worst violence was in Rotterdam

In Rotterdam, police used water cannon during clashes with rioters and Mayor Ahmed Aboutaleb signed an emergency decree, giving police broader powers of arrest.

He reacted furiously to reports of looting, condemning “shameless thieves, I can’t call it anything else.”

Football fans of the Willem II club took to the streets of Tilburg to “protect their city” against rioters, news site Brabants Dagblad reports.

The violence on Sunday was described by Dutch police as the worst unrest in four decades.

A Covid-19 testing centre was also set alight on Saturday evening in the northern village of Urk, local authorities said.

Police arrested a 39-year-old man in Almere on Saturday for posting threatening messages about journalists online, Dutch news agency ANP reported.

Mayors in several cities have vowed to introduce emergency measures in an effort to prevent more disturbances.

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image captionThe windows of some shops were smashed in Rotterdam

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image captionThe violence has been described as the worst for 40 years

“It’s unacceptable. All normal people will regard this with horror,” the prime minister told reporters.

“What motivated these people has nothing to do with protesting, it’s criminal violence and we will treat it as such.”

The Dutch government has introduced its toughest measures since the start of the pandemic – including a night-time curfew which runs from 21:00 (20:00 GMT) to 04:30. It is the first in the Netherlands since World War Two.

Anyone caught violating it faces a €95 (£84) fine.

The country’s bars and restaurants have been shut since October, while schools and non-essential shops closed last month.

A ban on flights from the UK, South Africa and South America has been put in place due to fears over new variants of the virus.