"Tens of thousands of protesters are expected to march through London tomorrow ahead of the G20 summit, amid mounting concern that over-aggressive police tactics may incite violence when world leaders gather to discuss the global economic meltdown.

"Yesterday, the Metropolitan police was understood to have contacted a number of protest groups warning that the main day of protest, Wednesday, 1 April would be 'very violent', and senior commanders have insisted that they are 'up for it, and up to it', should there be any trouble."