During an investigation by The Times in conjunction with one of the country’s top computer security experts, we identified 46 potentially vulnerable phones in the Central Lobby of the Palace of Westminster that could have been remotely activated and used as listening devices.

Using Bluetooth wireless technology installed in most mobile phones now on the market, we had the ability to access the handsets and have them secretly call us back. Once a connection was made, we could have listened to any conversation near the victims’ phones.

Almost as alarming, we had the capability to download all the text messages stored on the phones, establish which belonged to MPs and then initiate diverts to numbers of our choice so that we could have received all their incoming calls and pretended to be them.

The security flaw is caused by the abuse of the commonly available Bluetooth wireless technology.

This is the industry-standard name for software that allows telephones and computers to communicate via radio waves instead of along cables.

Two weeks ago, The Times revealed that the phone books, diaries and picture stores of some of Britain’s bestselling mobile handsets could be accessed using a laptop computer, some as-yet secret software and a wireless antenna or “dongle”.

The latest revelations go much further and are likely to cause grave concern among handset manufacturers, phone networks and the security industry.

In repeated tests conducted with Adam Laurie, the chairman of A.L. Digital — the computer security company that identified the flaws — we were able to:

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