Russia's communications regulator Roskomnadzor has blocked popular Chinese messenger WeChat and its website, the RosKomSvoboda NGO announced on its website on Friday.
The most popular mobile messaging applications in Russian Federation past year were Mail.ru's VKontakte, Facebook's WhatsApp and Rakuten's Viber, according to consultants J'son & Partners.
According to the Global Times, WeChat officials said Friday it feels sorry the app was blocked in Russia, and that the company is communicating with Russian authorities on this issue.
Russian Federation requires internet service providers to register with related government bodies, but Tencent "had a different understanding" on this issue, the company said in a statement.
Currently, some WeChat users in Moscow have been unable to log in or send messages.
Previous sites that have been blocked by Article 15.4 include messenger BlackBerry, Imo, Line, Vchat video chat and online radio Zello, according to a report by RBC TV.
Last year, Russian Federation blocked popular professional networking site LinkedIn as it allegedly failed to comply with the rules.
China also has strict internet regulations.
The huge success has helped boost Tencent's market capitalisation to more than US$300 billion, making it the most valuable Chinese company by market capitalization and putting it on par with Apple and Google-parent Alphabet.
Tencent became China's most valuable firm in September, beating state-owned telecom behemoth China Mobile and almost reaching half of Apple's valuation.
Sanctions are stipulated in Russia for "organizers of information distribution on the internet" for failure to comply with the Russian law on information, information technologies and information security.