State-controlled Rosneft reached an in-principle agreement with BP to buy its half of TNK-BP for $17.1 billion in cash and 12.84 percent of Rosneft's shares. In a separate deal, Rosneft agreed to take on the 50 percent stake in the venture held by Alfa-Access-Renova, the Russian side of the joint venture, for $28 billion.
Putin said the deal "will ensure further transparency of the activity of our largest (oil) company," reports state-run news agency RIA Novosti.
Putin met with BP stakeholders to express support for the deal.
Russian Energy Minister Alexander Novak told RIA Novosti last week that Rosneft's action wouldn't create market problems, saying "there is quite tight competition in a large market."
The Rosneft acquisition solidifies government control over the Russian energy sector. The acquisition means Rosneft, by calculations provided by Bloomberg News, controls about 40 percent of Russia's oil production.