Lawyers estimate that claims would be comparable to those filed by smokers against the tobacco industry for damaging their health with cigarettes.
At least six leading manufacturers - including Ericsson and Alcatel - clearly state on patent documents for new phone components that they are aimed at reducing health risks.
An application by Hitachi for an antenna states that the purpose of the device is to prevent "the health of the user from being injured". Patent applications submitted by other firms mention the reduction of "health risks" and maintaining "safe distances" between the user's body and "radiating systems".
Several of these applications date back more than five years which, experts say, suggests that the companies concerned must have suspected for a considerable time that mobile phones are a health risk.
The manufacturers have publicly denied their products are dangerous, despite growing concerns to the contrary. In a recent study, scientists found up to 70 per cent of mobile emissions could be absorbed by the head to create "hot spots" in the brain.
The industry is worth pounds 14bn annually to the UK. There are more than 200 million mobile phone users in the world, with 10.5 million in the UK. The figure could reach a billion by 2005.
According to Tom Jones, a partner in Thompsons, Britain's biggest personal injury law firm, the patent applications will be integral to future civil actions against the industry, as evidence it knew about the health risks.
Mr Jones is pursuing the first claims against mobile phone manufacturers to be launched in this country. "The mere fact these companies are producing modifications with a reduced risk must mean there was an increased risk with the product they were marketing at the time.
"This is a smoking gun and could be the basis for future litigation which could run into billions of pounds."
Roger Coghill, a biologist, believes manufacturers have been deliberately deceiving the public. He is pursuing a test case against one shop for allegedly failing to warn customers of the potential radiation risk and has recently published research on alleged damage to the immune system caused by mobile phones.
"These companies deny there is any health risk, yet they are all the time applying for patents to reduce the level of [microwave] emissions," he said. "If only 5 per cent of users in the UK used their phones excessively, that is half a million people at risk."
His views are backed by John Simpson, manager of Microshield, which makes radiation shields for mobile phones.
"These patents are clearly the acknowledgement by the cellular industry that there might be a risk because they have all been working on devices which specifically claim within the patent that their purpose is to reduce health risks."
But according to manufacturers, the patent applications were simply a response to current and future health guidelines. A spokesman for Alcatel did concede its choice of words was unfortunate: "We could have chosen better wording on these patents. We take them out so we are ready to bring products to the market to comply with standards should they change. But as far as we are concerned there is no scientific research which proves any damage could be done."
A spokesman for the Federation of the Electronic Industry said: "The handsets on the market are designed to be safe as long as they work within international guidelines... The mention of health risks on these patents refers to the fact that safety cannot be ensured below these guidelines."Reuse content