* Vadim Yakovlev named chairman, succeeds William Guinness
* Igor Tsibelman named CEO, succeeds Stuard Detmer
* 3 non-executive directors also appointed (Adds detail)
LONDON, Aug 12 Russian oil and gas explorer Sibir Energy SBE.L said on Wednesday its chairman and chief executive have both stepped-down from the board.
In a statement it said William Guinness would be succeeded as chairman by non-executive director Vadim Yakovlev, while Igor Tsibelman, previously deputy CEO, would become CEO in place of Stuard Detmer.
The appointments reflect the control over the business of Gazprom Neft (SIBN.MM), the oil arm of the the world's largest gas company Gazprom (GAZP.MM), which has acquired ownership over a majority of the voting rights of Sibir's shares.
Sibir also announced the appointment of three non-executive directors -- Dmitry Bekker, Maxim Viktorov and Andrei Martianov.
Bekker is a representative of The Central Fuel Company and the Moscow city government, while Viktorov and Martianov are nominees of The Central Fuel Company and Gazprom Neft, respectively.
Trading in Sibir's shares was suspended in February on London's AIM after it was revealed that debt from property deals of one of its main shareholders, Shalva Chigirinsky, was higher than had previously been announced. [ID:nLJ308825]
(Reporting by James Davey; Editing Bernard Orr)