Some mobile phone shields can "significantly reduce" exposure to radiation, according to a Government report published today.

Boffins looked at a number of products which claim to reduce exposure including shielded cases, earpiece pads and shields, antenna clips and caps, and absorbing buttons.

Tests found that many of the shield devices can reduce exposure to radiation by large amounts. However, any reduction is often linked to a similar reduction in mobile phone performance leading to a weaker signal.

The best-performing gadgets proved to be personal hands-free kits. According to those behind the report On the Effectiveness of Various Types of Mobile Phone Radiation Shields by separating the phone's antenna from the user's head, exposure to radiation is greatly reduced.

In a belt and braces recommendation, the report suggests that people use a hands-free kit while ensuring that the phone is not placed in contact with other parts of the body.

So, a shielded case clipped to a belt, for example, plus a hands-free kit would help to reduce exposure.

So too would using a mobile phone less - or even better - not at all.

The report also found that under standard exposure tests absorbing devices known as 'buttons' do not reduce mobile phone exposure.

Said the report: "The reductions are unidirectional and the small amounts of absorbing material are not particularly effective.

"Without specific understanding of how phones work, it is possible that much is taken on trust without reliance on any sound physical basis for the benefits claimed." ®

The report is due to be published on the DTI's Web site here.