About 200 protesters had gathered for Saturday's demonstration in the Hague in Netherlands
Police on Sunday said they had arrested 166 radical left-wingers at a protest in the Dutch capital The Hague over police violence.
About 200 protesters had gathered for Saturday's demonstration, organised under the slogan "Stop oppression against anti-facists and anarchists".
The city had approved the rally as long as people left their faces uncovered.
"At the start of the demonstration, a number of protesters covered their faces with scarves, hoods and sunglasses," the police said in a statement.
After they refused to unmask, the Mayor ordered the event to end.
"A group of 166 protesters resisted, and were arrested for breaking the law on public demonstrations," they said.
Illegal fireworks, paint bombs, sticks and a hammer were found on the ground when police moved in to make the arrests.