Gabon lifted a ban on the main opposition party, the Union Nationale, the interior ministry said Wednesday, enabling it to put forward a candidate against President Ali Bongo in next year's election.
The Union Nationale's former leader, Andre Mba Obame, refused to recognize Bongo's victory in a 2009 vote that followed the death of long-ruling President Omar Bongo, Ali's father. Instead, he declared himself to be victor, and two years later the state forcibly dissolved his party, with Mba Obame himself accused of high treason.
Mba Obame has been frequently absent from the central African country for health reasons since then, and it was not immediately clear who would lead the Union Nationale.
Former African Union head Jean Ping is currently the main opposition figure in the oil-producing state, although recent torture charges brought against him endanger his political future.
Gabon's president 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.
Falling oil prices have cut revenues, which may make it difficult for Bongo to deliver on housing and education pledges.
Still, he is widely seen as the favorite for the 2016 election, and some analysts said the lifting of the ban could actually further divide an already fragmented opposition.
"The more candidates you get standing against Bongo, the more divided the opposition vote becomes, favoring the incumbent, who has well-established party networks and superior resources," said Roddy Barclay, senior Africa analyst at consultancy Control Risks.
Under Gabon's political system, there is only one voting round, making it harder for Bongo's political opponents to rally around a single candidate, as can happen in the second round in other countries such as France.