Terry Myerson, who runs Microsoft's operating systems unit, announced the plan at the WinHEC technology conference in Shenzhen, China.

"We are upgrading all qualified PCs, genuine and non-genuine, to Windows 10," he said in a telephone interview with Reuters. The plan is to "re-engage" with the hundreds of millions of users of Windows in China, he said, without elaboration.

Microsoft in January had said it would offer free upgrades to Windows 10 for users of Windows 7 and higher operating systems in an attempt to hold onto users and make up for lost revenue by selling services such as Office over the Internet. At that time without further clarification it was expected the free upgrade offer would be limited to users of genuine Windows software.

In China, the company has partnered with Lenovo, Tencent and Qihu 360 to make the upgrade easy for consumers in country, said company during WinHEC conference.

"Strategic partnerships with Lenovo, Tencent and Qihu 360 will help Windows 10 reach hundreds of millions of customers in China and spur adoption of Windows 10 worldwide," noted Mayerson on Windows blog.

With Lenovo, Microsoft will offer Windows 10 upgrade services at 2,500 service centres and select retail stores in China. With Tencent, the free Windows 10 upgrade will be offered to its customers on Windows 7 and Windows 8.1 in China, and it will include QQ, Tencent Video and Tencent PC Manager as part of the free upgrade pack.

-NDTV