The possible threat to privacy posed by RFID tags has led to calls by the EU Commission for assurance that the tags can be turned off if desired.

EU Information Society Commissioner Viviane Reding said today at a conference in Brussels that Europeans are worried about the chips' broadcasting people's personal information and the consequential loss of privacy if this happens.

These RFID tags can be used for a wide variety of useful purposes, such as identifying livestock or luggage and even pointing out if food is past its sell-by date.

They are increasing being used by companies and retailers to monitor goods as they move along supply chains. Governments are also starting to think about putting them in many identity documents such as passports; Germany and the US already do this.

With an estimated 270 billion-plus RFID tags likely to be sold around the world by 2016, according to the EU, Reding warned the potential pros could be outweighed by the perceived cons.

"The majority are willing to be convinced that RFID can bring benefits, but they want to be reassured that it will not compromise their privacy," she said. "This is the deal that we have to strike if we want RFID to be accepted and widely taken up."

She said people need to keep control of how their information is used and updated - and how the tags can be turned off.

Only 15 per cent of the groups and individuals who took part in the six-month EU survey believed, however, that the matter of privacy should be left up to the industry to self-regulate.

The European Commission could therefore put forward a draft law on the subject in 2007.