Facebook has admitted that it had hired a PR firm to expose policies of Google that "raised privacy concerns" by planting "publicly available" data in the US media. However, the social networking company rebuffed reports that it asked the firm to run a smear campaign against Google.

The secret moves by Facebook were exposed after a blogger approached by PR firm Burson-Marsteller leaked an e-mail exchange.

Initially, the PR firm did not disclose the details of its client but did so after Facebook admitted to it.

A Facebook spokesman told the Daily Beast that the company was against Google’s attempts to use Facebook data in its own social networking service, Google Circles.

"Instead, 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.

A spokesman for Burson-Marsteller Paul Cordasco told the Guardian that it was not a standard procedure for his company and that it was actually against company’s policies.

Cordasco said, "Now that Facebook has come forward, we can confirm that we undertook an assignment for that client."

He added, "The client requested that its name be withheld on the grounds that it was merely asking to bring publicly available information to light and such information could then be independently and easily replicated by any media."

Cordasco also said that any information brought to media attention raised fair questions, was in the public domain, and was in any event for the media to verify through independent sources.

But Cordasco clarified that such practices were against the PR firm’s policies.

"Whatever the rationale, this was not at all standard operating procedure and is against our policies, and the assignment on those terms should have been declined," he said.

Google has not commented on the matter so far.