Usmanov, a Kremlin ally, is one of two men who have come to dominate media ownership in Russia, and increasingly the social media, since President Vladimir Putin rose to power in 2000.
His Internet holding group Mail.Ru said it had increased its stake in VKontakte, Russia's answer to Facebook , to around 52 percent by buying 12 percent of VKontakte (VK) shares from Megafon Chief Executive Officer Ivan Tavrin.
Mail.Ru already owns Russia's No. 2 and 3 social networking sites - Odnoklassniki (OK) and Moi Mir (My World) - and the deal for a further stake in VK gives it effective control over the top three social media in Russia.
Usmanov, worth $18.6 billion according to U.S. magazine Forbes, also owns Russian business daily Kommersant among other investments in telecoms and an iron ore and steel producer.
Mail.Ru said in a statement that no changes to the operational control over VK were intended and that it did not plan to fully consolidate VK in its financial statements.
Russia, with the largest Internet audience in Europe, has tightened monitoring of user-generated content since activists used social networks to organise protests over the December 2011 parliamentary election, which handed victory to Putin's ruling United Russia party.
The measures included launching a black list of sites distributing content such as child pornography, but which critics have said could boost censorship.For the latest tech news and reviews, follow Gadgets 360 on X, Facebook, WhatsApp, Threads and Google News. For the latest videos on gadgets and tech, subscribe to our YouTube channel. If you want to know everything about top influencers, follow our in-house Who'sThat360 on Instagram and YouTube.