Facebook's financial performance is stronger than previously believed, as the Internet social network's explosive growth in users and advertisers boosted 2009 revenue to as much as $800 million, according to two sources familiar with the situation.

The company also earned a solid net profit, in the tens of millions of dollars last year, one of the sources said.

That growth in profit and revenue underscores how Facebook is increasingly making money off its six-year-old service, which now ranks as the world's No. 1 Internet social network with nearly half a billion users.

Those results were significantly higher than the figures Facebook had guided toward last year as well as estimates in various analyst and media reports, which have generally pegged the company's 2009 revenue at between $550 million and $700 million.

Both sources said revenue was in the $700 million to $800 million range, which the first source said was more than double the 2008 level.

Facebook declined to comment.

(Reporting by Alexei Oreskovic; Editing by Edwin Chan, Phil Berlowitz)