Texts 'are not secure'

Industry analysts said it was easy for hackers to "eavesdrop" on texts, which have grown in popularity partly because they are regarded as more secure than email.

Texts messages are now so widespread that the Conservatives are planning to send them to voters in the run-up to the next General Election - following Labour's successful experiment in 2001, which boosted their support among the under-25 age group.

Dario Betti, a senior analyst at market research company Ovum, said: "It is undoubtedly possible to listen in on text messages. You need a good team of hackers and a lot of knowledge about who you are targeting. But it can easily be done."

Text messages are sent in coded form as radio waves from a mobile phone handset to a nearby base station, and then on to an "SMS gateway" - essentially a computer that sends it to the recipient.

This computer was the weakest point in the chain, said Mr Betti.

He added: "Any employee with access to this computer can read whatever text messages he wants.

"The only problem is that they will have to sift through so many messages - there are likely to be millions going through the system every hour - so you need to know what you are looking for."

Mobile phone company O2 recently sacked two employees who took advantage of this system to read text messages.

But most companies claim their systems are strictly policed and that encryption devices make hacking into text messages and reading them impossible.

Olly Winkhouse, a mobile phone security expert with consulting firm @stake, is not convinced and believes there are still many flaws in mobile phone security.

He said: "I can't comment on specific network operators but there are obvious flaws in the system that allow employees to monitor any message they want. There is no question that the British networks contain vulnerabilities that leave them open to hacker attacks. We have known about these for a few years and it is possible to listen in on text messages."

The other key concern about text security is how they can be used to impersonate a user. It follows claims that text messages allegedly proving an affair between David Beckham and his PA, Rebecca Loos, may have been faked by a computer hacker.

Mr Winkhouse said: "There are programmes on the internet you can download which will let you send

texts that appear to come from another user. All you need is that person's mobile number and you could easily send a message that would appear to come from him."

The phone industry sought to play down the security fears raised by industry experts.

A spokesman for Vodafone, which has the biggest share of Britain's mobile phone market, said: "We keep text messages for 21 days but they are encrypted and held by a third party company. Only if the police want access would we even consider decrypting the messages."

Mike Short, chairman of the industry's representative body, the Mobile Data Association, said: "We want to reassure customers that their messages are safe. Network employees don't read people's text messages any more than the Royal Mail reads people's letters. Reading people's text messages is extremely difficult at the network level."