Protests ahead of the G20 summit in London have been marred by scenes of violence as a group of demonstrators confronted police in the City of London.
Several hundred protestors tried to force their way through lines of officers, who hit back with batons.
Some protestors have smashed windows in the Royal Bank of Scotland.
Scotland Yard said 19 arrests have been made during the G20 protests.
11 people were arrested this morning after officers found police uniforms in the back of an armoured vehicle parked in the City of London.
Other arrests were for violent disorder, threatening behaviour, indecency, and one for possessing class A drugs.
Dozens of police officers congregated around the Tube stations as the activists began to grow in numbers.
All police leave in London had been cancelled.
Workers in the financial district had been advised to dress down, avoid provoking demonstrators and even stay away from work for the day.
