Met police using surveillance system to monitor mobile phones
Britain's largest police force is operating covert surveillance technology that can masquerade as a mobile phone network, transmitting a signal that allows authorities to shut off phones remotely, intercept communications and gather data about thousands of users in a targeted area.

The surveillance system has been procured by the Metropolitan police from Leeds-based company Datong plc, which counts the US Secret Service, the Ministry of Defence and regimes in the Middle East among its customers. Strictly classified under government protocol as "Listed X", it can emit a signal over an area of up to an estimated 10 sq km, forcing hundreds of mobile phones per minute to release their unique IMSI and IMEI identity codes, which can be used to track a person's movements in real time....