Tesco to snap every shopper

Tesco supermarket is testing a "Big Brother" anti-theft system which takes pictures of everyone buying high-value products in a bid to stop shoplifting.

A microchip the size of a grain of sand is attached to each product and - when someone removes that product from a display - an instore CCTV camera is triggered.

Civil liberties campaigners have criticised the experiment, and protested outside the Cambridge-supermarket where it is being carried out. They described the pilot, by Tesco, as an infringement of privacy and called on shoppers to boycott the chain until it drops the idea.

The CCTV images are destroyed once a product passes through the checkout and is paid for. Otherwise they can be retained to identify and possibly prosecute thieves. Police are said to be "impressed" with the quality of the images.

The products used in the trial are Gillette Mach 3 razor refills, which are shoplifted more often and in greater quantity than any other products in Europe. They cost up to £6.97 each, but can be easily concealed because the packs are relatively small.

Marks & Spencer, Woolworths and Asda are said to be planning to introduce the microchips, with many other stores expected to follow suit.

But the technology has already provoked a backlash in the US.

Benetton dropped plans to use the chips in pullovers following a threatened international boycott.

Outside the Tesco store in Cambridge, one protester, Damien Lawson, warned: "If this trial is successful a broader range of goods will be tagged.

"Tags could be buried in clothes and other items, and you could be bristling with chips. You would be transmitting - without your knowledge - personal information about where you shop, what you buy and how you pay. This could be retrieved by anyone with the proper equipment."

He added: "If enough customers make their concerns known then we hope Tesco will drop this."

Tesco spokesman Greg Sage said the scheme was designed to keep track of products within

the store, and insisted that the chips would not be used once those products left the premises.

He pledged: "We would never compromise the privacy of our customers.

"The system was designed to improve the availability of products to customers by enabling us to say exactly how many items are left on the shelf. Also, it makes life easier for staff to track exactly where items are."

The chips are in the packaging and will be discarded when the customer unwraps the product, Mr Sage said.

"The chips can only be read within a Tesco store - and in any case they only contain an eight-digit number, in the same way that a barcode contains a number."