Protesters camp in London, St Paul's forced to close

Dean Graeme Knowles wrote an open letter to protesters asking them to leave the square, which they have occupied since last today.

"We have done this with a very heavy heart, but it is simply not possible to fulfill our day to day obligations to worshippers, visitors and pilgrims in current circumstances," Knowles said in a statement.

Fire and health hazards posed by the camp - which has been steadily growing through the week - make it impossible for the cathedral to legally remain open, he added.

What started as a few dozen tents soon grew to a self-styled city - with its own university, library, canteen and toilets - governed by a burgeoning bureaucracy.

The camp was initially spared from clearance by the church, when Cathedral authorities told police officers to back off and allowed the protest to remain for its first night.

The protests are one of a number across Europe which draw their inspiration from similar demonstrations in New York.