Facebook founder is world's youngest billionaire (AFP)

NEW YORK (AFP) - Mark Zuckerberg, the 23-year-old founder of social networking site Facebook, is the youngest ever self-made billionaire, according to an annual list published by Forbes magazine.

"He is the youngest billionaire in the world right now and we also believe he is the youngest self-made billionaire in history," said the magazines Associate Editor Matthew Miller, unveiling this years super-rich list.

The magazine put the former Harvard students personal wealth at 1.5 billion dollars, based on what it said was a conservative valuation of five billion dollars for Facebook and Zuckerbergs estimated 30 percent stake.

It played down speculation that the site could be worth as much as 15 billion dollars, which was based on Microsoft paying 240 million dollars for a 1.6 percent stake in the company last year.

"Would it really fetch that much today? Some analysts -- and a few Facebook investors -- doubt it," the magazine said. It said it based its valuation on Facebooks estimated annual sales of 150 million dollars.