Tencent, the Chinese messaging service, has announced in a blog post that it is dropping support for Windows 10 Mobile, the version of the operating system that works on phones.
According to Tencent, Microsoft has not made enough effort to retain Windows users, many of whom have gone to iOS or Android.
"Users on the Windows Phone platform keeps declining and have moved to other platforms, but [we] didn't notice that Microsoft is showing any effort to retain them," the company said.
The comments are damaging because Tencent's QQ service, which is available in China and other Asian markets, has over 850 million users. WhatsApp, which is owned by Facebook, has 900 million users, for comparison.
Tencent develops apps for all other major platforms, including Windows (on desktop), OS X, iOS, and Android, but will not make a Windows 10 Mobile app.
Microsoft announced that it had sales of just 4.5 million Lumia devices during the holiday quarter of 2015, down more than 50% year-over-year. According to research firm Kantar, the only market Windows phones are doing well in is Britain. Chinese market share sits at around 1.2%.
