A new device to prevent crooks from spotting customers' PIN numbers is currently being tested in stores and could help to reduce card fraud, according to experts.

The PED Cradle, designed by Warwick University researchers, is a magnifying lens that can be fitted on top of the chip and PIN keypad. It was originally designed to help partially sighted customers use the ubiquitous devices but also improves security by distorting the image of the keypad to anyone but the person standing directly in front of the lens.

Boots the chemist is currently trialing 35 of the cradles at one of its city centre stores. Andrew Moloney of RSA Security's consumer solutions division, said the justification might be more about boosting consumer confidence in Boots’ brand than any financial benefit.

"The financial liability for fraudulent use of payment cards lies with the banks, so in some respects Boots installing this technology is a good-will gesture," Moloney argued. "Chip and PIN is a good [primary security measure] but we also recommend banks to employ transaction monitoring capabilities to pick up fraud more quickly."

Sandra Quinn of UK payments association Apacs said that it was natural for firms to regularly roll out new versions of chip and pin readers, the technology advances.

"A lot of organisations aren't using the same terminals they were two years ago," said Quinn. "There are always likely to be improvements on the market and it's a good opportunity for businesses to offer better, more robust and attractive [devices for their customers]."

The security of chip and PIN technology has come under scrutiny in recent weeks. Shell suspended the use of chip readers across its petrol stations, after fraudsters stole more than £1m from customer bank accounts by implanting skimming devices into the readers.

David Porter of IT security consultancy Detica welcomed the new technology but argued that it should have been engineered into card readers from the start. "It's a good idea but [it is a] fix to a problem that should have been identified [years] ago," he said. "I hope the developers of the next generation of anti-fraud technology are taking heed of this."

Porter added that the development would probably push criminals into finding other ways of obtaining consumers' PIN numbers.