OAKLAND, Jan 29: Dozens of police maintained a late-night guard around City Hall in Oakland, California, following daylong protests that resulted in 300 arrests. Earlier, Occupy Oakland demonstrators broke into the historic building and burned a US flag, and officers earlier fired tear gas to disperse people throwing rocks and tearing down fencing at a convention centre.

An exasperated Mayor Jean Quan, who faced heavy criticism for the police action last fall, called on the Occupy movement to "stop using Oakland as its playground."

"People in the community and people in the Occupy movement have to stop making excuses for this behaviour," Quan said.

Protesters clashed with police throughout the day, at times throwing rocks, bottles and other objects at officers. Police responded by deploying smoke, tear gas and bean bag rounds, City Administrator Deanna Santanta said.

Interim Police Chief Howard Jordan said about 300 arrests were made.

"These demonstrators stated their intention was to provoke officers and engage in illegal activity and that's exactly what has occurred today," Santana said.

The group assembled outside City Hall late Saturday morning and marched through the streets, disrupting traffic as they threatened to take over the vacant Henry Kaiser Convention Centre.

The protesters walked to the vacant convention centre, where some started tearing down perimeter fencing and "destroying construction equipment" shortly before 3 p.m., police said.

Police said they issued a dispersal order and used smoke and tear gas after some protesters pelted them with bottles, rocks, burning flares and other objects.

The number of demonstrators swelled as the day wore on, with afternoon estimates ranging from about 1,000 to 2,000 people.-AP