The monitoring centre for Russia's public communications network said on Tuesday its specialists had recorded a "massive failure" of Telegram, Russia's most popular messaging tool.
Telegram did not immediately reply to a request for comment.
Reuters correspondents in Moscow noted outages of Telegram, YouTube and Vkontakte for about 90 minutes.
"The work of Telegram messenger and a number of other services in Russia is already being restored," Russia's digital ministry said in a statement, adding that there had also been failures of the app outside Russia.
"Together with Roskomnadzor, we are working to establish the cause of the incident," it said.
Communications regulator Roskomnadzor has moved to block many foreign tech companies from operating in the country since the start of the war in Ukraine, including Meta Platforms' Facebook and Instagram.
Russia has long sought to improve its domestic internet infrastructure, or Runet, even disconnecting itself from the global internet for tests.
Anton Gorelkin, deputy head of the State Duma parliamentary committee on information policy, said it was unclear what had caused the Telegram outages but that immediately blaming the Russian state was a mistake, noting "conspiracy theories" that Russia was trying to block foreign resources prior to a March presidential election.
"There have been, and will be, such incidents for a variety of reasons: from human error to hacker attack," he said.
"Much more important is how long it takes to eliminate the failure; the scale of damage to the Russian economy depends on this."
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