Young children need to be protected from the potentially harmful effects of mobile phones, the UK's principal radiation monitoring agency has warned.

The National Radiological Protection Board (NRPB) said that children and other vulnerable groups should not be encouraged to use mobiles because of fears that adverse health effects could emerge after years of prolonged use.

Although the NRPB study concludes that there is no hard evidence at present that the health of the public is being affected adversely by the use of mobile phones, it cautions that "uncertainties remain and a continued precautionary approach" to their use is recommended until further research can be conducted to clarify the dangers.

The NRPB advises that "particular attention" should be given to how best to minimise exposure of potentially vulnerable groups such as children to mobile radiation.

It also warns that the government should act to protect other sub-groups within the population that may be particularly sensitive to radio waves.

Sir William Stewart, chairman of the NRPB, said: "The widespread use of mobile phones is a relatively recent phenomenon and it is possible that adverse health effects could emerge after years of prolonged use.

"The evidence base necessary to allow us to make firm judgements has not yet been accumulated. But because of the current uncertainties we recommend a continued precautionary approach to the use of mobile phone technologies.

"This approach should be adopted by all involved in this area, including government, the mobile phone industry and all who choose to purchase a mobile phone for themselves or their family or their children."

The board said that the planning process associated with the erection of mobile phone base stations should be subject to independent review.

It also suggested that monitoring of potential exposure from 3G base stations should be carried out concomitantly with the rollout of the network.

Additionally, a formal inspection procedure should be set in place to ensure that exclusion zones around base stations are clearly identified.

The board also places high importance on accumulating knowledge of exposure levels, and the possible biological effects of Tetra-based radio technology used by the police.