Britain's military will be armed with a sonic device that can be used as a high-volume loudspeaker or a non-lethal weapon to disperse crowds at this summer's Olympic Games in London.
The defence ministry's confirmed the equipment, which can project a piercing sound over hundreds of metres causing physical pain, will be used primarily in loudspeaker mode to communicate with boats it wants to stop on the River Thames.
Defence chiefs have already caused controversy by announcing plans to put surface-to-air missiles on the top of residential buildings near the Olympics site in east London.
Fighter jets roared over the capital and helicopters were seen hovering over the Houses of Parliament this month during a nine-day military exercise to prepare for Britain's biggest peacetime security operation.
