Microsoft CEO Steve Ballmer has said four times as many Windows Phone devices are currently being sold compared to a year ago, driven by the introduction of the latest version of the OS designed for more powerful handsets.

According to Bloomberg, Ballmer said in a shareholders meeting that Windows Phone 8 “is off to a great start” in its first few weeks of availability and initially sold out in many countries. However, he didn’t specify the actual number of phones that have been sold.

Ballmer added that there are now 120,000 Windows Phone apps available and that smartphones using Windows Phone 8 from Nokia and HTC have had “rave reviews”.

Windows Phone 8 is closely related to the Windows 8 OS used on PCs and tablets – including Microsoft’s own Surface – and shares the tiled homescreen design.