The latest and most powerful IMSI Catcher models can intercept and listen to phone calls, collect and read text messages and emails and block phone signals in a specific area

Tens of thousands of innocent people are having their mobile phones snooped on by police officers using ­secretive and controversial surveillance technology.

The Times can disclose that the Metropolitan police, the country’s largest force, uses devices called IMSI Catchers that “hoover up” the identity, call and message data of mobile phones.

The latest and most powerful IMSI Catcher models can also intercept and listen to phone calls, collect and read text messages and emails and block phone signals in a specific area.

The devices are deployed to uncover the phone activity of suspects but automatically capture information from all active mobiles within their range.

There is no automatic deletion of material gathered through “collateral intrusion” and police are thought to have stored details of many