Facebook will sell stock in a IPO when the time is right, CEO Mark Zuckerberg said in an ABC TV interview, addressing persistent speculation about its stock market debut.

Zuckerberg -- who with friends dreamed up the world's largest social network in a Harvard dorm room -- told ABC he was quite sure he had signed no contract handing over ownership rights to the company, disputing a claim to an 84-percent interest.

Last month, Paul Ceglia of Wellsville, New York, sued Zuckerberg and Facebook Inc, claiming a 2003 contract with Zuckerberg to develop and design a website now entitled him to a majority stake in the privately held company.

If we said that we were unsure, I think that was likely taken out of context, Zuckerberg told ABC's Diane Sawyer. Because I think we were quite sure that we did not sign a contract that says that they have any right to ownership over Facebook.

A slice of Facebook -- which recently signed up its 500 millionth member -- is a keenly sought-after piece of real estate. Investors are keen to get in on a company backed by the likes of Elevation Partners, Digital Sky and Microsoft and estimated to be worth billions of dollars.

Asked about when the company might go public, he told ABC News' Diane Sawyer: When it makes sense, right. I mean, what we're most focused on is just building these tools that help people stay connected with the people that they care about.

And at some point along the path, I think it'll make sense to have an IPO. But we're not running the company to do that.

Combining a large audience of Web surfers with innovative online advertising has become a recipe for super-charged revenue growth in the Internet business.

Facebook ranks among the Web's most popular sites, alongside Google Inc, Yahoo Inc and Microsoft Corp . The privately held company is also one of the most closely-watched Web operators by investors to jump onboard a blockbuster initial public offering.

Sources have told Reuters it raked in as much as $800 million of revenue in 2009 and made tens of millions of dollars in profit in 2009.

(Reporting by Edwin Chan; Editing by Sofina Mirza-Reid)

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