WeChat, launched in 2011, is not hugely popular in Russia but the blockage may affect Chinese tourists and Russians doing business with China.
In Russia, WeChat is no more.
"WeChat did not provide the contact information necessary for registration with authorities", Xinhua news agency quoted Vadim Ampelonsky, spokesman of Russian telecommunication watchdog Roskomnadzor, as saying on Friday.
Chinese internet giant Tencent said Saturday it was "deeply sorry" its messaging app WeChat was blocked in Russian Federation, adding it was in touch with authorities to resolve the issue.
"We're experiencing a block and we're deeply sorry", a company official said on a Tencent microblog. According to Russia's regulation on Internet management, online service providers must have to register with related government bodies in the country, while WeChat had a different understanding over the issue.More news: AAP averts crisis, Kumar Vishwas made Rajasthan chief, Amanatullah Khan suspended
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Russia's telecom watchdog announced earlier this week that WeChat is not in compliance with Russia's information laws.
A law passed in 2014 requires foreign messaging services, search engines and social networking sites to store the personal data of Russian users inside Russia. It is produced by China's IT giant Tencent.
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.
Roskomnadzor also said on its website that the authorities blocked the WeChat app because it failed to discharge various responsibilities the law imposes on organisers of information distribution on the internet.