THE HAGUE, Netherlands (AP) — Hundreds of climate activists blocked one of the main roads into The Hague on Saturday, defying attempts to prevent their protest that have sparked concerns about restrictions on the right to demonstrate in the Netherlands.

The protesters, many waving coloured flags with the symbol of environmental group Extinction Rebellion and one holding a sign saying, in Dutch, “This is a dead end road,” gathered on the A12 road near the temporary home of the Dutch parliament. Police and hundreds more demonstrators looked on.

About an hour after the blockade began, officers began arresting demonstrators who refused to leave the road.

Earlier this week, six Extinction Rebellion activists were detained by authorities on suspicion of sedition linked to calls to stage the protest. A judge on Friday upheld an order banning another activist from the area for 90 days.

The arrests and exclusion order sparked unrest among activists who argue it infringes their right to peaceful protest.

Extinction Rebellion spokesperson Anne Kervers said the large number of participants “shows what society thinks of fossil fuel subsidies and of the intimidation and criminalization of nonviolent climate activism.”

Prosecutors defended their action, saying the suspects were calling for supporters to take part in the “dangerous and disruptive blockade” of the road.

“Calling for a criminal offence — such as blocking a public road — amounts to sedition,” prosecutors said in a statement.

They said that the blockade of the busy road leading into The Hague was a danger to motorists and protesters.

“Demonstrating is a fundamental right and is facilitated by the municipality of The Hague,” prosecutors said. “There are hundreds of demonstrations in The Hague every year that go off without a hitch. But a demonstration is not a licence to commit criminal offences.”

Extinction Rebellion activists, however, vowed to continue with their protests, in which they demand an end to government tax breaks for companies linked to fossil fuels.

“It is essential that citizens can demonstrate against this in a place that matters. For Extinction Rebellion, this includes the A12, between the House of Representatives and the Ministry of Economic Affairs and Climate,” the group said in a statement. “Any nuisance for traffic, for example, will have to be tolerated.”

Other activists joined the protest out of solidarity.

“We are very concerned that the right to protest is being increasingly restricted in the Netherlands. We stand firmly behind peaceful activists who exercise their right to protest,” Andy Palmen of the Dutch arm of Greenpeace said in a statement ahead of the demonstration.