The number of militant activists arrested at a chaotic Palestine Action protest have soared to more than 530 people.

During a day of mayhem and farce, Left-wing protesters swamped London's Parliament Square on Saturday in support of the organisation, which was proscribed by the Government last month as a terrorist group.

Hundreds held placards declaring 'I oppose genocide. I support Palestine Action' in deliberate 'idiotic' acts of law-breaking designed to overwhelm police resources and the courts.

Last night, the Metropolitan Police announced more than 360 people had been detained following the scenes of disorder - at an estimated cost of about £3million.

Protesters were accused of a 'colossal' waste of millions of pounds of taxpayers' money after seemingly getting deliberately arrested by officers.