About an hour after the blockade began, officers began arresting protesters who refused to leave the road.
Earlier this week, six Extinction Rebellion activists were detained by authorities on suspicion of incitement in connection with calls to stage the protest. A judge on Friday upheld an order barring another activist from entering the area for 90 days.
The arrest and detention order sparked unrest among activists who claim it infringes on their right to peaceful protest.
Extinction Rebellion spokesperson Anne Kervers said the large number of participants “shows how society feels about fossil fuel subsidies and about the harassment and criminalization of nonviolent climate activism.”
Prosecutors defended their action, saying the suspects called on supporters to participate in the “dangerous and disruptive blockade” of the road.
“Calling to commit a criminal offense — such as blocking a public highway — amounts to sedition,” prosecutors said in a statement.
They said the blockade of the busy road to The Hague posed a danger to motorists and demonstrators.
“Demonstrating is a fundamental right and is facilitated by the municipality of The Hague,” the prosecutors said. “There are hundreds of demonstrations in The Hague every year that go off without a hitch. But a demonstration is not a license to commit criminal offenses.”
However, Extinction Rebellion activists vowed to continue their protests, demanding 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. “All nuisance for traffic, for example, will have to be tolerated.”
Other activists joined the protest in solidarity.
“We are very concerned that the right to demonstrate in the Netherlands is being increasingly restricted. We stand firmly behind peaceful activists exercising their right to protest,” said Andy Palmen of the Dutch branch of Greenpeace in a statement ahead of the demonstration.