The Mobile Telecommunications and Health Research Programme (MTHR) has received £8.8m in funding from the government and communications industry.

It has carried out 28 separate studies into the health impact of mobile phones, masts and base stations.

These include looking at the impact on childhood cancer, brain tumours, blood pressure and general brain function.

There are now 70 million mobile phone handsets in the UK, and around 50 thousand masts.

Both emit radio signals and electromagnetic fields that can penetrate the human brain, and campaigners fear that this could seriously damage human health.

The MTHR programme was established following publication of an independent government-commissioned report into the safety of mobile phones in 2000.

The report, produced by a group led by Sir William Stewart, concluded that mobile phones did not appear to harm health - but recommended further research was carried out.

However, in 2005 Sir William warned that mobile phone use by children should be limited as a precaution - and that under-eights should not use them at all.

Mixed findings

Many other studies have also been carried out - with mixed results.

These include a major 2006 study by the Danish Institute of Cancer Epidemiology of more than 420,000 mobile phone users, which found no evidence that mobile phone use was linked to an increased risk of cancer.

These findings echoed work by the Institute of Cancer Research, also published in 2006, which concluded that mobile phone use was not associated with a greater risk of brain cancer.

Earlier this year, the idea that mobile phone masts can trigger symptoms such as anxiety, nausea and tiredness in sensitive individuals was dismissed by a study led by the University of Essex.

But a US study found heavy use of mobile phones may damage men's fertility.

Scientists in Finland carried out tests suggesting electromagnetic radiation affects human brain tissue.

And in 2004, a 750-people study by Sweden's Karolinska Institute found using a mobile phone for 10 years or more increases the risk of ear tumours by four times.