600,000 Xbox 360's sold in the US to date - NPD

The Xbox 360 has sold 600,000 units in the United States since it launched there in late November, according to market research firm NPD Group, which revealed the figures late last week.

Stock shortages of the console have severely restricted its sales in North America and Europe, even in the wake of Christmas, and some retailers are believed to have unfulfilled preorders even now.

However, Microsoft is bringing a new factory on line to produce the Xbox 360 next month, and hopes to be able to deliver new stock to the market at a faster rate by the end of this quarter.

The software giant revised its shipment targets for the Xbox 360 at the start of this year, and now expects to ship between 4.5 and 5.5 million units of the console worldwide by the end of its financial year on June 30th.