Facebook said former FTC chairman Tim Muris hasn’t joined the company, contrary to widespread reports that the Bush administration official was becoming part of the social network’s growing lobby shop. Facebook is still looking for a second senior lobbyist to join its D.C. office of four, according to Andrew Noyes, who manages public policy communications for the social network.

The Financial Times reported earlier today that Muris is helping the company defend its privacy practices before lawmakers and regulatory agencies as it faces extra scrutiny.

Facebook may be paying Muris as a consultant or as an outside attorney. The company wouldn’t comment on the arrangement. Certainly Muris’s relationships and know-how inside the FTC would come as an asset.

In any case, Facebook has rapidly grown its presence on Capitol Hill during the last year to try and explain its value to lawmakers and to influence legislation that might curb its data collection or ad targeting abilities. It hired Tim Sparapani from the American Civil Liberties Union last year along with Noyes, who was a long-time technology policy reporter. A fourth employee, Corey Owens, said he joined in March.

Facebook’s moves come at a time when lawmakers are paying increased attention to social networking and its implications for privacy.

Rep. Rick Boucher (D., Va.) and Rep. Cliff Stearns (R., Fla.) unveiled a discussion draft of a consumer privacy bill earlier this month while Sen. Chuck Schumer (D., NY) wrote a letter to chief executive Mark Zuckerberg last month that criticized the company’s new instant personalization program, which automatically shares data with pre-selected partners. It worked on an opt-out, rather than opt-in model. Schumer said he would sponsor legislation that would give the FTC greater power to regulate privacy issues, if the agency didn’t feel it had enough authority.