Microsoft Corp sold more than 2 million units of its new Windows Phone 7 software to handset makers last quarter, a strong start for the new software launched in October, but still far behind Apple Inc's iPhone and Google Inc's Android system.

The world's largest software maker, which licenses the technology to handset makers such as Samsung Electronics Co Ltd, LG Electronics Inc and HTC Corp, also said there were now more than 6,500 apps for download by users from its online marketplace.

The numbers show pretty good momentum on the sales of the platform, said Al Hilwa, an analyst at tech research firm IDC. Anecdotally almost everyone who has seen the phone has commented on the style and fluidity of the interface. The apps numbers are excellent for this early stage of the lifecycle.

Despite the strong start, Microsoft still lags its main rivals in the smartphone market.

Apple said last week 16.2 million iPhones were sold in the last quarter. Research in Motion Ltd said in December it sold 14.2 million of its BlackBerry smartphones in the quarter ended November 27.

Google, which gives away its Android system to phone makers for free, says 300,000 Android devices are sold daily, which suggest more than 9 million are sold a month.

Microsoft is set to report quarterly earnings on Thursday. Its shares closed up 33 cents, or 1.2 percent, to $28.78 on Nasdaq.

(Reporting by Bill Rigby, editing by Gerald E. McCormick and Carol Bishopric)