Russia's communications providers on Thursday blocked access to the website of opposition leader Alexei Navalny on orders of the state communications watchdog.
Navalny announced the move via his Twitter account, which was still accessible. Users going to the website were told it could not be reached.
The agency, Roskomnadzor, had demanded that Navalny remove a video alleging that Deputy Prime Minister Sergei Prikhodko received lavish hospitality from billionaire Oleg Deripaska.
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Deripaska rejected the report and won a court ruling that ordered Navalny to remove the investigation as an unlawful intrusion into the tycoon's privacy. Navalny refused, and appealed the ruling.
A statement Thursday from Deripaska's Basic Element company said: "Mr. Deripaska's claim is to protect his right to privacy, and has nothing to do with any political struggle between Mr. Navalny and his political opponents."
Navalny's investigation drew from the social media account of a woman who claims to have had an affair with Deripaska.
The woman, who calls herself Nastya Rybka, has written a book about her work as an escort and said on Russian television last year she had been hired by a modeling agency to spend time at Deripaska's yacht.
Instagram on Thursday had removed some of Rybka's posts following Roskomnadzor's request, but a YouTube video of Navalny's investigation that has generated over 5 million views remained available.
Rybka posted several videos in 2016 showing Deripaska on his yacht talking with Prikhodko. In one snippet, Deripaska explains to the woman why relations between Russia and the United States are so bad.
Deripaska has been linked to U.S. President Donald Trump's former campaign chairman, Paul Manafort, who has been indicted in special counsel Robert Mueller's investigation into Russian meddling in the 2016 U.S. election.
Navalny, the most vocal critic of Russian President Vladimir Putin, wanted to run against him in Russia's March 18 presidential election, but was barred because of a fraud conviction in a case that many see as politically motivated.