Climate activists blocked a major traffic artery in the Netherlands on Saturday, the latest in a series of demonstrations against government subsidies on fossil fuels.

With policing of the protest light due to a strike, around 500 activists marched onto a highway that leads into the centre of The Hague, seat of the Dutch government, around midday.

Accompanied by drums, protesters chanted "the oceans are rising and so are we" and carried banners saying "Action Now" and "Stop Fossil Subsidies."

Some of the protesters brought camping chairs and set up tents on the spot to indicate they were planning to stay overnight.

Last year, a government report estimated that industrial companies receive more than 39 billion euros ($43.2 billion) in subsidies on fossil fuel, mostly in the form of tax breaks. The climate protest group Extinction Rebellion has vowed to continue protesting until subsidies are removed.

More than a dozen protests organised by the group have taken place at the same location on the A12 highway over the past year. In the past, authorities have forcibly removed protesters after several hours and detained those that ignore orders to leave.

However, with most police on strike until 5 p.m. (1500 GMT)on Saturday due to a pension dispute, it was not clear how long the protest would continue.

The City of The Hague said in a statement that blocking the highway is forbidden and protesters should move to a large field nearby.