The Russian government blocked Facebook Meta Platforms Inc in response to Facebook's restrictions on access to Russian media on the platform.
The regulator, Roskomnadzor, said there had been 26 cases of discrimination against Russian media by Facebook since October 2020, including restrictions in recent days on state-backed channels such as RT and the RIA news agency.
The move is a major escalation in the ongoing confrontation between big tech companies and Russia, which in recent years has issued numerous fines and teetered services through a slowdown.
Tensions are rising amid Russia's invasion of Ukraine, which Moscow calls "special operations".
The Tass news agency reported on Friday that Russia had restricted access to Twitter. The Interfax news agency previously said the service had been blocked.
Twitter Inc did not immediately respond to a request for comment.
Meta's head of global affairs, Nick Clegg, said the company would continue to do everything possible to restore its services.
"Soon millions of Russians will find themselves cut off from reliable information, deprived of their daily way of connecting with family and friends and silenced from speaking out," he said, in a statement posted on Twitter.
Last week, Moscow said it was partially restricting access to Facebook, a move the company said came after it rejected government requests to stop independent fact-checking of some Russian state media. On Saturday, Twitter also said its service was restricted to some Russian users.
Big tech companies have faced pressure to respond to the February 24 invasion, which has led to economic sanctions against Moscow by governments around the world. Russia's state-run media have emerged as a major flashpoint between Moscow and social media platforms during the conflict.
Meta this week said it had restricted access to RT and Sputnik across the European Union and globally took down content from the Russian state-controlled outlet's Facebook pages and Instagram accounts, as well as posts containing links to those outlets on Facebook. Tech companies such as Google Alphabet Inc (GOOGL.O) have also temporarily suspended advertising in Russia.
Russia has taken several steps to crack down on foreign news media in recent days. It cut off access to several news organisations' websites, including the BBC, Voice of America and Radio Free Europe/Radio Liberty for spreading false information about its actions in Ukraine.
The Ukrainian government has asked Meta and other platforms during the conflict to withdraw their services from Russia. Online speech experts and rights advocates have raised concerns about the impact of blocking online services on Russian citizens trying to organize or obtain information.
Meta had about 7.5 million users on Facebook in Russia last year and 122.2 million users across other services, including Instagram, WhatsApp and Messenger, according to estimates from Insider Intelligence. Russia's leading social network, VK, has 63 million users, according to researchers' estimates.
The popular VPN app has been downloaded more than 1.3 million times in Russia since its invasion of Ukraine began, according to data from researcher AppFigures, which describes the figure as a huge spike.
Meta is also one of several tech companies facing possible punitive action in Russia after they failed to open local offices and take other actions required by a communications law passed this summer.
Tech companies globally have pulled out of Russia in response to requests from governments or to signal support for Ukraine. US internet provider Cogent Communications (CCOI.O) said on Friday it was cutting internet service to Russian clients.
Earlier this week, business software giant Oracle Corp said it was suspending all operations in Russia, while rival SAP SE said it would temporarily halt all sales in the country. A Ukrainian government official has tweeted at both companies asking for support.
Roskomnadzor said in its statement that Meta had restricted access to accounts of state-backed news outlets in recent days, lists RT, Sputnik, RIA news agency, the defense ministry's Zvezda TV and the sites gazeta.ru and lenta.ru.
It said the restrictions violated the main principles of freedom of information and unhindered access of Russian internet users to Russian media.
