A violent mob targeted a Royal Bank of Scotland building in the City of London today as the G20 protests spiralled into violence.

Windows were smashed and a group of demonstrators - their faces covered by bandanas - entered the building near the Bank of England.

Around the branch, which is believed to be empty, hundreds of demonstrators charged police lines as officers hit back with baton charges.

A group of 4,000 were penned in by officers who cordoned off surrounding streets amid what Scotland Yard called "increasing levels of violence".

At least one officer was injured as RBS became a flashpoint for what had been peaceful protests.

A printer and other office equipment was thrown out of the window and graffiti daubed on the side of the building.

Hundreds of protesters cheered as a blue office chair was used to smash one of the blacked-out branch windows.

At around 2pm a line of police - backed up by a line of mounted officers - began to slowly attempt to move protesters back down Bartholomew Lane and into Threadneedle Street.

Demonstrators continued to hurl missiles at broken windows at the RBS and attempted to break down a door.

Police in riot gear could be seen inside the building, filming the demonstrators.

One protester with a megaphone yelled: "Push the police back. These are our streets."

The demonstrators then began to chant: "Our streets."

Protesters also let off a fire extinguisher into a broken RBS window.