By Marcus Leach

Social networking site Facebook has been exposed for a smear campaign against fierce rivals Google.

An email exchange published by one blogger confirms that Facebook hired a PR firm to instigate anti-Google stories relating to user privacy.

PR firm Burson-Marsteller had been touting stories for an unnamed client concerning the Google service 'Social Circle', although blogger Chris Soghain opted not to pursue the story, and instead published the email exchange between himself and Burson-Marsteller.

The publication of the emails sparked a host of rumours as to who the client could be, with both Microsoft and Apple firmly in the frame.

However, US-based news site 'The Daily Beast' were the ones to reveal that the client was in fact Facebook, who were quick to confirm that they had used Burson-Marsteller to expose things that Google was doing relating to privacy concerns, but denied they had authorised a smear campaign against their rivals.

"We wanted third parties to verify that people did not approve of the collection and use of information from their accounts on Facebook and other services for inclusion in Google Social Circles, just as Facebook did not approve of use or collection for this purpose," the company said.

Burson, in their email exchange with Mr Soghain, had said "the American people must be made aware of the now immediate intrusions into their deeply personal lives Google is cataloguing and broadcasting every minute of every day - without their permission."