At least 30 people were arrested during Saturday’s rioting during an anti-immigration demonstration in the centre of The Hague, and more arrests will follow, police said at a press conference.

Two police officers were also injured in the fighting, which was instigated by “hooligans,” The Hague’s mayor Jan van Zanen said. The violence, Van Zanen told reporters, “was unprecedented and unworthy of the Netherlands.”

“Groups of hooligans from all over the country deliberately sought confrontation with the police,” he said. “And they used extreme violence.”

The trouble began when a group of 1,500 protesters attempted to blockade the nearby A12 motorway, ignoring appeals from organisers not to do so. Many of them were dressed in black, some covering their faces with balaclavas.

Some of those who attended displayed far-right symbols such as the prinsjesvlag, a forerunner of the Dutch national flag with an orange stripe, which is associated with the pre-war Dutch Nazi party (NSB).

Demonstrators clashed with police on the Malieveld, throwing stones and bottles and setting a police car on fire. A press photographer covering the protest was taken to hospital after being punched in the face.

One group broke away at around 3pm and headed towards the Binnenhof parliamentary complex, which is currently being renovated, where they were involved in a stand-off with riot police.