Chelsea FC owner Roman Abramovich today agreed to sell Russian oil company Sibneft for £7.36 billion.
Gazprom, the world's biggest natural gas producer, will purchase 72.7 per cent of Sibneft, taking its stake in the company to more than 75 per cent.
An agreement was signed today between Gazprom and Sibneft's owner, Millhouse Capital, a holding company controlled by Abramovich (38).
The purchase by Gazprom, which has been under state control since June, is the biggest in Russian corporate history.
It significantly boosts Gazprom's stature in the oil sector and President Vladimir Putin's efforts to recapture Kremlin influence in the lucrative energy industry.
Gazprom, which already owns 3 per cent of Sibneft, Russia's fifth largest oil company, has long been groomed as a state energy giant to rival Saudi Arabia's Aramco.
Western banks were reported to be ready to offer a £6.79 billion loan to fund the deal - the largest such loan in Russia's post-Soviet history.
Gazprom shares gained 1 per cent today as Russia's benchmark stock exchange index broke through the 1,000 point mark for the first time in its 10-year history.
Over the last three months, the Russian Trading System has risen by 45 per cent, fuelled in part by an oil-driven boom. The Russian government sold off Sibneft in 1996 for 100 million dollars and it eventually ended up in Abramovich's control.
Gazprom did not give details of how it was funding the deal today, but the purchase of Sibneft is expected to more than quadruple its crude oil output to 1.17 million barrels a day.
It is thought that the deal could give the Kremlin control of around 30 per cent of oil pumped in Russia.
Gazprom management committee chairman Alexey Miller said: "We've been consistent in meeting the strategic challenge of diversifying our business portfolio and transforming Gazprom into a world-class energy company.
"The oil business is a core activity of Gazprom. Given the obvious synergy, Gazprom and Sibneft's businesses will enhance Gazprom's operating efficiency, both in Russia and global oil and gas markets."