Up to 300 people have been arrested in the US after an Occupy protest turned violent.
Police rounded up demonstrators in Oakland, California, after demonstrators broke into the City Hall and burned the American flag.
Officers fired tear gas and used flash grenades to disperse a crowd of up to 2,000 people after some demonstrators also threw rocks and bottles during the chaos on Saturday.
It was the most turbulent day of protests since November, when Oakland police forcefully dismantled an Occupy encampment.
Mayor Jean Quan, who faced heavy criticism for the police action last autumn, called on the Occupy movement to "stop using Oakland as its playground".
The international Occupy Wall Street movement, which denounces corporate excess and economic inequality, began in New York City in the autumn.
It spread to London in October, with protesters camping outside St Paul's Cathedral.
Oakland, New York and Los Angeles were among the cities with the largest and most vocal Occupy protests early on.
Authorities used force to move out hundreds of demonstrators who had set up tent cities, and the protests have been largely dormant lately.
In Oakland, the police department was criticised for using force to break up earlier protests.
Among the critics was the mayor, who said she was not briefed on the department's plans.
The demonstration comes after Occupy protesters said earlier this week that they planned to move into a vacant building and turn it into a social centre and political hub.
They also threatened to try to shut down the port, occupy the airport and take over City Hall.
City administrator Deanna Santana said the city would not be "bullied by threats of violence or illegal activity".