LIBREVILLE (Reuters) - Andre Mba Obame, once one of Gabon's leading opposition figures, has died in neighboring Cameroon following a prolonged illness, his National Union political party said on Sunday.
Mba Obame served as an advisor to longtime President Omar Bongo, eventually rising to the post of minister of the interior. However, he broke with the ruling party to run for the presidency as an independent following Bongo's death in 2009.
Though official results handed victory to the late leader's son, Ali Bongo, Mba Obame declared himself the winner, leading the authorities to accuse him of treason.
"This is an immense loss for the National Union, the Gabonese opposition, and for our country Gabon," a statement from the party said, adding that Mba Obame had died around noon on Sunday in Cameroon's capital, Yaounde. He was 57 years old.
Mba Obame joined the opposition grouping not long after the 2009 election and served as its executive secretary, though the government outlawed the party two years later.
The ban was lifted in February, clearing the way for it to put forward a candidate against President Bongo in next year's election.
Mba Obame has been frequently absent from the central African oil-producing nation for health reasons since 2009 and it had not been immediately clear who would lead the National Union.
Former African Union head Jean Ping is currently the main opposition figure in the oil-producing state although recent torture charges brought against him have clouded his political future.
Bongo has faced mounting criticism in recent months over a range of grievances and trade union disputes, leading to violent demonstrations in December in which one protester was killed.
(Reporting by Gerauds Wilfried Obangome; Writing by Joe Bavier, editing by David Evans)