The kind of surveillance activities carried out on behalf of computing giant Hewlett-Packard which caused controversy last year have been made illegal in the US thanks to a new law.

President George W Bush has signed an Act which outlaws pretexting, the practice of gaining information about a third party's phone use without their permission.

The federal legislation signed by Bush was the Federal Telephone Records and Privacy Protection Act. It creates criminal penalties for "the fraudulent or unauthorised acquisition or disclosure of confidential phone records information," according to a statement from the White House.

The Act was approved by the Senate in December of last year and was signed by Bush on Friday. It creates penalties of up to 10 years in prison for anyone found to have broken the law. The punishment can be doubled if the activity is found to be on a large scale, which the Act defines as involving more than $100,000 or more than 50 victims.

Though the legislation was passed by the House of Representatives in April 2006 before being held up by the Senate, it became high profile news when HP's activities came to light.

An inquiry into leaks from HP's board resulted in the use of pretexting to discover details of board members' private telephone calls on non-HP phones. The activity, which was carried out by firms contracted directly or indirectly to HP, became public last August and prompted an outcry.

It later emerged that people acting for HP had also obtained phone records of journalists, had sent a fake email to one with a surveillance code in it and had even physically tracked one journalist.

HP chairwoman Patricia Dunn resigned over the affair and a federal prosecution is ongoing. In that case one investigator, Bryan Wagner of Colorado, has just pleaded guilty to identity theft and conspiracy charges.

Wagner's lawyer said that Wagner would testify on behalf of the prosecution in what is a major victory for prosecutors in their attempts to trace the charges back to more senior investigators and perhaps to HP itself.

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