A study using volunteers who had dummy mobile phones strapped to their heads while carrying out psychological tests has overturned the popular view that the telephones cause people to forget things.
In the only research in the world on the effects of mobile phones on the human brain, scientists from Bristol University found that the phones significantly improved the speed it took to carry out mental tasks.
Although it does not address concerns about potential cancer risks, the surprise findings will come as a comfort to the estimated 10 million users of mobile phones in Britain who have been subjected to a series of scare stories about the potential mental effects caused by microwaves from their handsets.
Alan Preece, the Bristol researcher who carried out the study, funded by the Department of Health, is understood to have briefed the Government about the results.
Dr Preece used 36 volunteers who wore a special helmet fitted with a mobile phone on the left side. They carried out a series of psychological tests lasting between 25 and 35 minutes whilst the power was switched either on or off.
He found that people were just as good - or bad - at memory tests whether the power was running or not.
However, he also discovered that it took people less time to react to a stimulus when the power to the mobile phone was switched on.
This was more evident when the emissions from the experiment were designed to mimic an analogue mobile rather than the newer digital phones.
Although Dr Preece has refused to comment on the research until is it published in the International Journal of Radiation Biology, one suggestion is that this might be caused by stimulating the part of the brain's left hemisphere that acts as a communications channel between the centres of vision and speech.
The study's preliminary findings have been misreported by a number of national newspapers, claiming that mobiles cause memory loss. Dr Preece said that the reports are "substantially inaccurate" and "based on pure guesswork".
Research by other scientists has centred on test-tube studies or laboratory rats. Their equivocal findings, however, have failed to substantiate controversial reports that mobile phones cause cancer, amnesia and other problems.
Britain's radiation watchdog, the National Radiological Protection Board (NRPB), has said: "There is no convincing scientific evidence of a health risk to humans resulting from mobile phone use."
However, it is supporting more "high quality" research to investigate the potential risks.