More than 1.5 million cellphones carrying Microsoft Corp's Windows Phone 7 operating software have sold in the first six weeks of launch, meeting what the company called realistic expectations.

Achim Berg, vice president of business and marketing for Windows phones, released sales numbers for the nascent platform for the first time in an internally conducted interview posted on Microsoft's Website.

Windows Phone 7 was unveiled in October and marked the software maker's expansion into a smartphone arena dominated by Apple Inc and Google Inc. Analysts say it could be Microsoft's last chance to establish a major presence in a hot market.

Taiwan's HTC, Dell Inc, Samsung Electronics and LG Electronics are among the vendors who have launched or plan to begin selling Phone 7-based devices.

We all know that the competition is extreme in this industry, and we have to compete on multiple fronts, Berg said in the interview.

We are on a path to begin releasing the first of several updates in the next couple of months, and several more mobile operators around the world will introduce Windows Phone 7 on their network in 2011.

Microsoft's disappearance from the phone market, and its delayed response to the emergence of tablet devices like Apple's iPad, has been seen as a drag on its shares this year.

(Reporting by Edwin Chan; editing by Gunna Dickson)