

The London Metropolitan Police Force uses a tracking appliance that can force mobile devices to cough up their unique IDs (IMEIs and IMSIs) and give the Met realtime views into who is where and who they're with. The devices can also intercept SMSes and effect denial of service attacks on handsets.

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.

The disclosure has caused concern among lawyers and privacy groups that large numbers of innocent people could be unwittingly implicated in covert intelligence gathering. The Met has refused to confirm whether the system is used in public order situations, such as during large protests or demonstrations.

Nick Pickles, director of privacy and civil liberties campaign group Big Brother Watch, warned the technology could give police the ability to conduct "blanket and indiscriminate" monitoring: "It raises a number of serious civil liberties concerns and clarification is urgently needed on when and where this technology has been deployed, and what data has been gathered," he said. "Such invasive surveillance must be tightly regulated, authorised at the highest level and only used in the most serious of investigations. It should be absolutely clear that only data directly relating to targets of investigations is monitored or stored," he said.