Russia has blocked access to Chinese social media app WeChat, developed by Tencent Holdings, for failing to give its contact details to the Russian communications watchdog.
Access to China's most popular social media platform has been restricted since May 4, according to information posted on the Russian regulator's website.
Last year, Russia blocked U.S. social networking site LinkedIn, owned by Microsoft, for violating a law that requires data on Russian citizens to be stored on Russian servers.
Vadim Ampelonskiy, spokesman for the Roskomnadzor watchdog, said on Saturday WeChat was blocked because it did not provide contact details for Russia's register of "organizers of information distribution on the internet."
Tencent told Reuters it was checking the status of WeChat in Russia and was in talks with the relevant authorities.
WeChat, launched in 2011, is not hugely popular in Russia but the blockage may affect Chinese tourists and Russians doing business with China.
Meanwhile social media applications such as Facebook and Twitter are blocked in China, with President Xi Jinping a vocal advocate of so-called cyber sovereignty.