Tesco has ended a trial of new technology that tracked customers buying Gillette razor blades. The retailer denied that the technology was being used for security reasons, but shoppers considered it to be an invasion of their privacy.

After Tesco's use of radio frequency identification (RFID) chips was revealed, protests were held outside the store and consumers wrote to Gillette demanding that plans to use the chips be shelved.

Gillette has reportedly backed away from introducing RFID chips into individual products on a wider scale, despite being an enthusiastic supporter of the technology. The company is heavily involved in the Auto-ID consortium, which is looking at ways of developing RFID for shops, but it says that chips may not be used to monitor individual products for at least 10 years.

Tesco said its Cambridge trial had finished as planned; it was only meant to be in place for six months from January, and decisions had not been affected by the protests. The company has now moved to its next phase in testing RFID, by placing chips in DVDs at its store in Sandhurst, Berkshire.

Barry Hugill, of the civil rights group Liberty, was concerned at "function creep", in other words, information recorded for one purpose being used for another.

We want clear legal guidelines as to what information companies, government agencies, local authorities are allowed to glean [and] what they can do with it.