* IPO unlikely before late 2012
* Will consider revenue, business model before IPO (Adds details of business, background on Thiel, byline)
By Alexei Oreskovic
SAN FRANCISCO, Sept 27 Facebook, the world's largest online social network, is likely to go public sometime after late 2012, a board member said, satisfying investors' appetite for a slice of one of the Internet's biggest growth stories.
A stock market debut by a company valued in the tens of billions of dollars would be one of the most highly anticipated initial public offerings of the decade.
But Facebook board member, venture capitalist and PayPal co-founder Peter Thiel stressed on Monday that will not happen until after late 2012, and would depend on the company hitting certain revenue targets and how its business model develops.
"It probably will IPO at some point. The lesson from Google (GOOG.O) seems to be that you don't go public until very late," Thiel told Reuters on the sidelines of the TechCrunch Disrupt conference in San Francisco on Monday.
Palo Alto, California-based Facebook, the booming social networking site dreamed up by Mark Zuckerberg and his buddies in a Harvard dorm room in 2004, is privately held and has released only nuggets of financial information.
With half a billion users and counting, it is closely watched by investors hoping to one day buy public shares in the fast-growing company. Sources have told Reuters its revenue approached $800 million in 2009 and it was already profitable -- a solid showing for a six-year-old service. [ID:nN1768699]
Still, the social network is increasingly challenging more established Internet players such as Yahoo Inc (YHOO.O) and Google Inc for consumers' online time and for ad dollars, even as it tries to strike a delicate balance between protecting privacy and promoting social sharing by its users.
Its backers now include Digital Sky Technologies, Microsoft Corp (MSFT.O), Hong Kong tycoon Li Ka Shing and venture capital firms Accel Partners, Greylock Partners and Meritech Capital Partners.
Thiel's comments were first reported by the Fox Business network. (Writing by Edwin Chan; Editing by Robert MacMillan and Richard Chang)