The supermarket chain Tesco has admitted testing controversial technology that tracks customers buying certain products through its stores. Anyone picking up Gillette Mach3 razor blades at its Cambridge store will have his or her picture taken.

The Guardian, alerted by Katherine Albrecht, director of US-based Consumers Against Supermarket Privacy and Invasion and Numbering, to the use of the smart electronic tags, has found that tags in the razor blades trigger ...