The amount of electromagnetic radiation produced by mobile telephones is below the level regarded as safe in Britain, according to research by Bradford University.
Researcher Peter Excell said all mobile phones were found to produce electromagnetic fields below the National Radiological Protection Board's basic restriction levels.
But he emphasised that the Bradford research project was concerned only with the electromagnetic fields in the human head caused by mobile phones and he had "no opinion" on the level of hazard they posed.
A NRPB spokesman said it was still not possible to determine whether mobile phones were safe or not.
The Bradford project, a Department of Trade and Industry Link programme, took three and a half years and cost almost Pounds 250,000.
It means there is an accurate method of predicting the level of electromagnetic radiation in human tissue and discovering whether mobile phone safety standards are being met.
As well as sophisticated computer modelling, the Bradford researchers also used a phantom head covered in simulated human skin and flesh to determine how electromagnetic fields produced by mobiles affected humans.
The head was manufactured by Microwave Consultants, an offshoot of King's College London.
The university hoped to conduct further research on the subject, Dr Excell said, because mobile phone usage would continue to increase.
The arrival of satellite-based networks and "mobile multimedia" early in the next millennium, which would require much wider bandwidths than conventional cellular phones, was another reason more investigation was needed.