The Hague, Netherlands (AP) – Hundreds of environmental activists blocked the main highway to The Hague on Saturday, defying efforts to stop protests that have stoked fears about limiting the right to demonstrate in the Netherlands.

Protesters, many waving flags colored with the emblem of environmental group Extinction Rebellion and one holding a sign reading “This is a dead end”, gathered on the A12 highway near the temporary seat of the Dutch Parliament. Police and hundreds of other protesters watched.

Protesters who ignored police orders to clear the road were loaded one by one onto departing buses. Hours after the start of the protests, it is not known how many people have been detained. Police tweeted that many of the activists quit voluntarily when asked to do so by officers.

A few days ago, authorities arrested six Extinction Rebellion activists on suspicion of sedition in connection with calls to participate in protests.

On Friday, a judge upheld an order banning other activists from the area for 90 days. Extinction Rebellion said they ignored the order and attended the protest. A lawyer for the group said the order was a way to “deprive environmentalists of the right to demonstrate.”

The arrests and exclusion orders have sparked outrage among activists who argue they violate their right to demonstrate peacefully.

Extinction Rebellion spokeswoman Anne Kervers said the large number of participants “demonstrates what the public has to say about fossil fuel subsidies and the non-violent intimidation and criminalization of environmental activists.”

Prosecutors defended their actions, noting that the detainees called on supporters to join in on a “dangerous and disruptive blockade” of the highway.

“Calling a crime such as blocking a public highway constitutes sedition,” prosecutors said in a statement.