Tesco has announced its plans to install a face-scanning technology to all of its 450 petrol stations in the UK to help target advertisements to customers at the till.

The technology, which was created by Lord Sugar's digital signage company Amscreen, will use a camera to identify a customer's gender and their approximate age that will then show an advert tailored to the customers demographic.

A Tesco spokeswoman said: "This is not new technology. No data or images are collected or stored and the system does not use eyeball scanners or facial-recognition technology".

Privacy campaigners said companies had to tell their customers they were using the technology.

Philip James, joint head of technology at Pitmans law firm, argues that the technology being used is very similar to the way social media sites tailor adverts to users based on the content of their profiles.

"The capture of facial signatures represents a potentially much greater infringement of customers' privacy in the absence of prior consent," he said.

The screens are expected to reach five million customers.