The move follows the announcement yesterday that Gazprom Neft had raised its stake in Sibir Energy to 33.5% from 28.5%, becoming the largest stakeholder by almost fully buying out Sibir's minority shareholders.

Today, Sibir said Igor Tsibelman was appointed chief executive to replace Stuard Detmer.

Tsibelman, 41, headed Gazprom Neft's international legal affairs department.

Prior to joining the company he worked as an attorney for White & Case and Arent Fox in New York.

Gazprom is widely believed to be aiming for control of Sibir, which ran into trouble last year after its main shareholder, Chalva Tchigirinsky, was forced to put up his stake as collateral with state bank Sberbank to meet obligations on Western loans.

Tchigirinsky and his partner Igor Kesayev jointly control around 47% of Sibir, a stake now collateralised with Sberbank, while the central government owns 18%.

Market sources have said Gazprom wants to buy out both Kesayev's and Tchigirinsky's stakes.

The fate of the latter is complicated by the fact that another Russian businessman, Ruslan Baisarov, claims ownership of it while Tchigirinsky has won a British court order prohibiting Gazprom and Gazprom Neft from buying those shares until their ownership becomes clear.

Meanwhile, it emerged Gazprom Neft's net profit fell 76% in the first quarter, but the results were slightly above consensus forecasts.

The company said in a statement its net profit calculated to US GAAP standards fell to $335 million in the first three months of 2009 compared to $300 million in a Reuters poll.

The company managed to recover from a net loss of $0.543 billion in final quarter of 2008 due to higher oil prices, lower tax bill and rouble devaluation.

Revenues fell by 48% to $4.185 billion compared to the same period a year ago, while earnings before interest, taxation, depreciation and amortisation (EBITDA) declined by 53% to $942 million.

Published: 18 June 2009 07:24 GMT  | Last updated: 18 June 2009 08:09 GMT