Mr Lockhart, who joins Facebook next month as Vice President of Global Communications, represents the company's latest move to enlist Washington insiders.

Mr. Lockhart was the chief spokesman and senior adviser to President Clinton between 1998 and 2000, according to the biography on the website of the Glover Park Group, a communications firm he co-founded in 2001.

"His experience building and running a press office at the White House gives him particular appreciation for the demands of a global 24-hour news cycle and the challenges of responding effectively to intense scrutiny,'' said Elliot Schrage, Facebook Vice President of Global Communications, Marketing and Public Policy, in an emailed statement.

Facebook, the world's No. 1 internet social network with more than 500 million people, has grown in influence in the internet industry as well as in the spheres of public policy and world affairs during its seven-year history.