According to the BBC, the officers said they were annulling the results of Saturday’s election which the opposition had denounced as “fraudulent”.
Twelve soldiers reportedly appeared on television to announce that they were cancelling the results of the election and dissolving “all the institutions of the republic”.
“We have decided to defend peace by putting an end to the current regime,” one of the soldiers was quoted as saying on TV channel Gabon 24.
The soldier cited “irresponsible, unpredictable governance resulting in a continuing deterioration in social cohesion that risks leading the country into chaos”.
The Gabonese Election Centre (CGE) had declared Bongo winner of the election on Wednesday with 64.27% of the votes cast.
Michel Bonda, CGE head, said Bongo’s main challenger, Albert Ossa, had polled second with 30.77%.
Bongo’s team have rejected Ossa’s allegations of electoral fraud and irregularities.
Tensions have been running high in Gabon with fears of unrest, following the presidential and parliamentary elections.
Bongo’s overthrow would end his family’s 53-year hold on power. He became president when his father Omar died in 2009.
Bongo suffered a stroke in 2018 which sidelined him for almost a year and led to calls for him to step aside.
In 2019, there was a coup attempt on Bongo. Soldiers who led the failed putsch were sent to prison.