Russia's telecom watchdog blocked WeChat along with several other websites.
WeChat, operated by Tencent Holdings, was out of compliance with Russia's law on information, information technologies and information security, the Russian Federal Service for Supervision of Communications, Information Technology, and Mass Media said Thursday.
Since late April, Roskomnadzor has blacklisted several websites and messaging apps operating in the country, including Blackberry Messenger, Imo and Line, citing regulatory transgressions. By the end of 2016, WeChat had 927 million registered users worldwide.
Tencent is aware of the move and is communicating with Russian authorities, the company said Friday in a statement. Russia requires internet service providers to register with related government bodies. But Tencent said in the statement that it "had a different understanding" of the issue.
"The Chinese community (in Russia) is quite worried about the news as most people are using WeChat for daily family and business contacts," said a Chinese WeChat user who lives in Russia. He said people are busy contacting each other to set up alternative communications such as Tencent's QQ and Whatsapp.
As of Friday, some WeChat users in Russia said the app seemed to be operating normally, but users of certain mobile network providers reported occasional problems, according to the source, who declined to be named.