An emergency plan to create a mobile-free “bubble” for the President was branded “hysteria” by Orange, the second-largest mobile phone provider. It said that the police had no power to compel Orange to switch off its transmitters.

Scotland Yard wants to prevent mobile calls and text messages whenever the President arrives or leaves Buckingham Palace.

But an Orange spokeswoman said: “The rules state that we only have to block phone calls in this manner when there is a national emergency. That means during a war. The visit of a foreign dignitary is not a national emergency. It’s Bush hysteria.”

Police sources said that they were considering introducing the measure during Mr Bush’s visit as mobile phones have been used to detonate bombs.

It is possible to bar mobile phone users from making calls in small areas by switching off individual stations. This can stop mobile telephone use across half a square mile in built-up areas and more in rural areas.

It is understood that the police carried out tests this week outside London to see if the technology worked. They are believed to have been successful. Scotland Yard would need approval from the Prime Minister and the Cabinet Office to implement such a measure.

However, mobile phone operators said that they would have the final decision over using the technology.

A spokeswoman for Vodafone said that the only time the police or the Government had the power to restrict the use of its network was during a national emergency.

At all other times the decision would rest with the company and they would not automatically comply with a police request to do so.

“If we are requested to do something, we would take that seriously but stopping the service to our subscribers is not something we would want to do lightly,” she said.

A spokesman for T-Mobile said that if the network received a request from the Home Office to help it to create a mobile-free zone, the company would “judge each suggestion on its merits”.

Blocking calls is not without precedent. The police are believed to have requested that calls were jammed in parts of Central London on Millennium Eve, amid fears that bottlenecks, including bridges, were becoming overcrowded.

According to Vodafone, restrictions on mobile telephone use were also introduced after the Potters Bar crash last year, following a request from the emergency services. Non-emergency calls around the station were barred for more than an hour. Senior officers said that it would be up to the Cabinet Office to deal with any claims for compensation from the telephone operators.

The plan being considered is to create a “sterile area” some 15 minutes before Mr Bush gets into his armoured Cadillac and 15 minutes after his return. Among the many demands made by the White House was a mobile telephone blackout whenever the President left Buckingham Palace.

US officials were kept informed of the tests carried out by Scotland Yard. It is understood that mobile users in the test area did not realise that the short break in signals was due to the experiment.

Senior officers insist that such a draconian step is to combat terrorists, though such a ban will disrupt the activities of militant anarchist groups who rely on their mobile telephones to co-ordinate attacks during mass demonstrations in the capital.

Scotland Yard admits that it is waging a high-tech battle with the groups to try to eavesdrop on their plans for disruption over the next three days. The worry is that they can send text-messages to alert small groups who have infiltrated the main march.

Internet-enabled phones can send more elaborate messages and maps with last-minute instructions, and some militants have made use of mobiles that can transmit pictures of where they want followers to gather. They would be rendered useless by the shutdown.

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