Reports Gavin Thomas for BBC News:
The Ministry of Defence has confirmed a device which can be used as a “sonic weapon” will be deployed in London during the Olympics.
The American-made Long Range Acoustic Device (LRAD) can be used to send verbal warnings over a long distance or emit a beam of pain-inducing tones.
The equipment was spotted fixed to a landing craft on the Thames at Westminster this week.
An MoD spokesman said it would be used “primarily in the loud hailer mode”.
Royal Marines operating in patrol craft from HMS Ocean are also heavily armed with conventional firearms.