A key opposition figure will return to Gabon after spending over a year in medical treatment in South Africa and France, his party's president said Monday.

"Andre Mba Obame will return (August) the 11th," said Zacharie Myboto, president of the National Union party, one of two main opposition groups and officially dissolved since last year.

Mba Obame had earlier said his return to the western African nation was imminent.

"Thirteen months after I left Gabon in a wheelchair, I will be back very soon on both legs," Mba Obame said late last month by telephone from France.

"Let those who reported me dead prepare to battle my ghost!" he added.

An interior minister under President Omar Bongo, Mba Obame ran for office after Bongo's death in 2009 but lost to his son Ali Bongo in elections he claims were rigged.

Having never recognised the official results, Mba Obame proclaimed himself president in January 2011, prompting the regime to officially dissolve his party.