ALGIERS, Sept 30 (Reuters) - Libya's NOC state oil firm on Wednesday announced the appointment of Ali Seghir Mohamed Saleh, until now the company's director-general, as its new boss.

"The Secretary of the General People's Committee (the Libyan government) issued a letter requiring brother Ali Seghir Mohamed Saleh to serve as Secretary of the Management Committee of the National Oil Corporation," the NOC said in a statement posted on Wednesday on its internet site.

The company has been without a fully-fledged head since the previous holder of the post, Shokri Ghanem, left earlier this month, causing concern for foreign oil majors who viewed him as a reliable partner in an often unpredictable country.

Industry sources said they did not expect Mohamed Saleh's appointment would draw a line under the uncertainty for the foreign oil majors in Libya, which include BP (BP.L: Quote, Profile, Research) and ExxonMobil (XOM.N: Quote, Profile, Research).

Mohamed Saleh represented Libya at a Sept. 9 meeting of OPEC energy ministers in Vienna. He stood in for Ghanem, whose unexplained absence had fuelled speculation that he was no longer in charge of the NOC.

Libyan official sources later confirmed Ghanem had left the job, but no reason has been given for the move.

ENTHUSIASM TEMPERED

Since Ghanem's departure, Azzam al Messallati, previously the de facto number 2 executive in the company, has been serving as caretaker boss.

International oil companies rushed to invest in Libya, home to Africa's largest proven oil reserves, after the lifting of international sanctions helped bring the country out of decades of isolation.

However, investors' initial enthusiasm has been tempered by modest results from exploration wells and concerns about the risks of dealing with Libya's government.

Some investors say the treatment of Canadian energy exploration firm Verenex (VNX.TO: Quote, Profile, Research), whose shares fell sharply after Libya denied approval for a takeover by an arm of China National Petroleum Corp., underlined Libya's unpredictability. [ID:nSP470412]

Secretary of the NOC Management Committee is the formal name used by the company for the post previously held by Ghanem. The NOC statement said Mohamed Saleh would combine his new role with his old duties as director-general. (Additional reporting by Alex Lawler in London; Editing by Keiron Henderson)

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