Details of the buyout of Russian petrochemical producer Sibur, a subsidiary of the state's largest national oil and gas producer Gazprom, by its management have shown the company is worth $4.6bn (€3bn).

Gazprom, which owns 70% minus one share of Sibur, has reached a preliminary agreement with five of Sibur's managers to sell 50% plus one share of the company. Gazprom will be given a right to sell the remaining 20% of its stake in the company via a put option within three years for $920m.