The protest by Extinction Rebellion (XR) activists followed several similar protests last year to demonstrate against Dutch fossil fuel subsidies and to highlight the effects of climate change.

"Some 700 activists were detained after the A12 highway was blocked off," The Hague police said on X.

"This led to traffic jams and longer travel times for ambulances and other emergency services," they added.

Police maintained a heavy presence with foot patrols, and on horseback, while a police drone hovered overhead.

Hundreds of protesters gathered around mid-day and walked onto the highway despite police attempts to stop several other activists, an AFP correspondent saw.

The protesters ignored a request from the city and police to remain on the Malieveld open ground in the city centre and not to enter onto the neighbouring arterial road.

Several hundred protesters carried banners and placards saying "We believe in life after oil" while waving XR flags however marched onto the road.

Two protesters also scaled a signboard beam spanning the A12 before unrolling an XR flag.

Several hours later police sprayed protesters with water cannons before detaining activists who were sitting on the main road.

Most were later released at a location near the ADO stadium on the city's outskirts, local news radio Omroep West reported.

Protester Christian Loncle, 49, said he believed "politicians are not doing enough yet" to fight climate change.

Referring to the current fires ravaging Los Angeles in California, Loncle said he was not a scientist to make a direct correlation between climate change and the blazes.

"But hopefully politicians are listening to us instead of waiting until their houses burn down."

Wildfires occur naturally, but scientists say human-caused climate change is altering weather and changing the dynamics of the blazes.

Last year in April, climate activist Greta Thunberg was detained twice during a similar march to protest against fossil fuel subsidies.