MOSCOW (AP) — Russia's communications oversight agency is moving to block access to an investigation published online by opposition leader Alexei Navalny alleging that Deputy Prime Minister Sergei Prikhodko received lavish hospitality from billionaire Oleg Deripaska.

The tycoon has been linked to President Donald Trump's former campaign chairman Paul Manafort, who has been indicted in U.S. special counsel Robert Mueller's investigation into Russian meddling in the 2016 U.S. election.

The agency, Roskomnadzor, said Saturday it has placed the investigation, which was published Thursday on the website of Navalny's Anti-Corruption Foundation, and a YouTube video of it, on its register of sites containing information not to be distributed in Russia, according to Russian news agencies.

The sites have three days after the notification to remove the material before being blocked.

Foundation lawyer Ivan Zhdanov says the move would be appealed in court.

Navalny is the most prominent foe of President Vladimir Putin. He intended to run against Putin in Russia's March 18 presidential race, but was barred because of a fraud conviction in a case that many see as being politically motivated.

Navalny's investigation draws 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 that she had been hired by a modeling agency to spend time at Deripaska's yacht.

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.

Navalny quoted public records suggesting that Prikhodko spent several days on the yacht and was flown there by Deripaska's private jet.

Navalny's foundation earlier published documents suggesting that Prikhodko, a long-time public servant with no significant private income, owns a luxurious mansion outside Moscow.

Deripaska's spokesman rejected Navalny's report.