The Ministry of Defence has confirmed a gadget which can be utilized as a Sonic weapon will be deployed in London in the course of the Olympics.
The American-made Long Assortment Acoustic Device (LRAD) can be utilised to send verbal warnings over a long distance or emit a beam of ache-inducing tones.
The gear was spotted fixed to a landing craft on the Thames at Westminster this week.
An MoD spokesman said it would be used â€œprimarily in the loud hailer modeâ€.
Royal Marines operating in patrol craft from HMS Ocean are also heavily armed with traditional firearms.The piercing beam of sound emitted by the gadget is highly directional. Some versions of the LRAD are capable of generating deafening sound levels of 150 decibels at one metre.
But the device, which was utilized this week during Exercising Olympic Guardian, can also be utilised to broadcast verbal warnings, such as ordering crowds to disperse.
The San Diego-based LRAD Corporation has previously offered the gadget to the US Army, which deployed them in Iraq for crowd control.