Smartphone maker HTC reportedly plans to make tablets based on the Windows operating system, giving Microsoft another ally in its challenge to Apple and Google.

Bloomberg today cited people familiar with the matter and reported that HTC has been working on a 12-inch device and a 7-inch version that can also make phone calls. The devices will run on Windows RT OS and will be powered by Qualcomm chips, the report added.

Previously, HTC had been considering a tablet with Windows 8 running on Intel chips (x86), but scrapped those plans because the company determined it would have to charge too much for the device.

Mircosoft and HTC have not commented on the report.

A 7-inch tablet would be the first of that size for Windows RT, and would be positioned to compete with the iPad mini, Amazon's Kindle Fire and Google's Nexus 7.

Nokia has been also rumored to prepare a Windows RT tablet.