Microsoft is reportedly experimenting with a free version of its current operating system, Windows 8.1, Digital Spy reveals citing The Verge.

The PC maker is planning a cut-down version called Windows 8.1 with Bing, aimed at luring users still using Window 7.

Aside from building numbers on the operating system, the main purpose is to drive the company's key apps and services.

It's claimed that the Bing-powered upgrade will be low-cost or even free if it is released.

This version could be offered to PC manufacturers as part of the alleged 70% licence fee reduction for Windows 8.1 that is thought to be in the pipeline.

There is also talk of Microsoft releasing a free version of its Windows Phone OS, following hints that it could merge with Windows RT.