A visitor tries out Microsoft Windows 10 operating system during a launch event in Tokyo, Japan on July 29, 2015. Photo: CFP

Microsoft is under fire in China as the company pushes users to upgrade their operating systems to Windows 10.

The pop-up upgrade window does not offer a "decline" option, only a choice to upgrade later. Computers running older versions of Windows will automatically start the upgrade at the recommended time if users ignore the pop-up without selecting the option to delay or cancel the update.

Yang Shuo, who works at a Beijing-based public relations company, said the sudden update interrupted him while he was drafting a business plan, which led to cancellation of a meeting for a deal worth 3 million yuan ($457,500).

"Just because I didn't see the pop-up reminder does not mean I agreed," said Yang, adding he did not even know when the installation package was downloaded to the laptop.

Yang is not the only one complaining about the unwanted update. On microblog site Weibo, posts related to Windows 10 reached more than 1.2 million.

"Can't you stop forcing users to update? Do you know how much work by graphic designers you have ruined?" wrote a graphic designer under the screen name 3jinyeshixin.

Microsoft technical support staff have posted instructions on the company's official Weibo account for users who want to revert to an earlier version of the operating system.

The company said earlier this month that more than 300 million devices have started using the Windows 10 platform and the free update will end on July 29.

Experts believe the aggressive update is being pushed as the company tries to secure market share in the face of competitors such as Google and Apple.

The company is expected to use Windows 10 as a platform for app development.

Zhao Zhanling, a legal advisor with the Internet Society of China, said Microsoft has not respected users' rights to know and choose, especially since the company may eventually profit from the unwanted upgrades.

"The company has abused its dominant market position," Zhao said.

He said users or consumer protection organizations have the right to file a lawsuit against the company.

Xinhua