^{June 17, 2001}

 illions of pounds of stealth warfare weaponry could be rendered obsolete by a system which uses existing mobile phone masts. According to researchers hi-tech, "invisible to radar" stealth fighters and bombers - which can cost £1.4 billion each - can be located using mobile signals and then shot down.

The system uses mobile calls between base stations to create a screen which is disrupted by stealth aircraft - and even by cruise missiles - flying through. Special receiving units the size of a Land Rover are used to detect disruptions in the signals.

The units cost just £100,000 each and will eventually be reduced to the size of a briefcase. The aircraft is pinpointed with the help of the existing global positioning satellite system, allowing it to be shot down.

The US in particular has invested billions of pounds developing stealth aircraft and they played an important part in both the Gulf War and Kosovo conflict. But the system being developed at the Siemens Group's Roke Manor research facility in Hampshire could render them obsolete very quickly.

Peter Lloyd, head of sensor projects at the centre, said: "Stealth technology could turn out to be the American Maginot Line" - referring to the line of fortifications built by France to defend its border with Germany before the Second World War that proved ineffective. He said the new defence system was a "spin off" from a commercial venture which would see the next generation of mobile phones having "locational aware systems".

That will allow a system to keep track of where a mobile phone is, leading to innovations like mobile users being sent information about cheap deals in shops they are walking by.