
Masked squatters demonstrate in the centre of Amsterdam. (AP Photo/Evert Elzinga)
The protests came as the once-respected Dutch tradition of squatting became illegal.
In Amsterdam, people demonstrated peacefully on Friday against the new law.
By nightfall, demonstrators began throwing rocks at police and vandalizing cars. Police tried to disperse large groups on two streets by charging.
Squatters used metal fences and bikes to block off one of the city's ancient canals amid a haze of tear gas. Police using bulldozers and water cannons tried to clear the streets and put out small fires set in piles of rubbish.