Voting has started in Gabon, where the president is trying to overcome a coalition of high-profile opponents to win re-election and maintain a family dynasty that stretches back to the 1960s.

Ali Bongo Ondimba took power in 2009 following the death of his father, Omar Bongo, who ruled the oil-producing country of about 1.5 million people for more than 40 years.

The most formidable challenge among nine opponents comes from Jean Ping, a former chair of the African Union Commission who managed to get several other aspirants to rally around his candidacy.

More than 600,000 voters are registered to participate.

Voting is scheduled to end at 6 p.m., with provisional results expected early next week.