The UK's police service is snooping on the mobile phone data of "tens of thousands of innocent people" with secretive new technology – a report published today claims.

According to the Times, the Metropolitan police – which is the country's biggest force – is deploying devices called IMSI Catchers that can detect the "identity, call and message data of mobile phones" and, at their most powerful, even listen in on conversations and read text messages.

The technology is used to track suspects but automatically collects information from all active mobiles within its range, the paper says.

It goes on to claim that this material is not automatically deleted and therefore police are thought to have stored details of "many thousands" of innocent people's phone activity.

No official police sources would confirm or deny the use of the technology, but the Times says it is understood it is only authorised to prevent and detect serious crime.