In the heyday of former President Omar Bongo, Gabon and its oil wealth were a central pillar of "La Francafrique", a shadowy network that enabled France's troops to defend African autocrats in exchange for juicy contracts for French companies.
Thanks partly to this web of diplomacy and trade backed by French firepower, Bongo stayed in office for 42 years before his death in 2009. France's energy firms, meanwhile, had undisputed claims to some of the continent's richest oil fields.
But the days of France throwing its weight behind a leader for commercial favours may be numbered, which presents a challenge for French businesses in West Africa, a largely Francophone region because of its colonial past
Ali Bongo, the son of the late president, was inaugurated for a second term on Tuesday after an election whose credibility EU observers seriously called into question.
France's position has been clear since the Aug. 27 poll: it has "doubts" about its credibility, so it won't endorse Bongo as the winner against his main opponent Jean Ping - a clear message that Bongo's half-century family dynasty can no longer count on support from Gabon's former colonial master.
Bongo denies unduly influencing the election, and Gabon's top court upheld the result.
Yet his father used to win elections with so little credibility that in 1986 he got over 99 percent of the vote, and four years later, when protests erupted, French troops stepped in to quell them.
France's Elf won every oil licence in a bidding round shortly after, according to British journalist Nicholas Shaxson in his 2008 book Poisoned Wells.
"That period is behind us," French Foreign Minister Jean-Marc Ayrault told the France 2 TV channel this month.
"We do not want ... to interfere in countries' internal affairs," he said, articulating a trademark policy of Socialist President Francois Hollande, who four years ago pledged that "the era of La Francafrique is over" while in Senegal.
A French diplomat told Reuters that current thinking in the French government was that Paris could no longer automatically back an ally, even when trade interests are at stake. If the leader's popularity fades, in elections or on the streets, France will distance itself.
"The era of us picking someone and saying 'you're the next president' is over," another French diplomat said, even when France has "specific interests in one country or another".
"France has changed quite a lot," said Paul Melly, associate fellow in the Africa Programme of London-based international affairs think-tank Chatham House.
"The time when the French intervened to help Omar Bongo ... that was the old La Francafrique, looking after your chums," he said, an approach that was now "basically impossible".
In Burkina Faso, where crowds ousted Blaise Compaore in 2014 as he tried to extend his 27-year rule, France backed away from its former friend, having quietly told him it was a bad idea.
Socialist Hollande has shown no interest in cultivating the decades-old clandestine networks linking French businessmen and intelligence agents to African politicians that were created by France's right-wing former President Charles de Gaulle.
"There really has been a shift to the idea that if there are to be negotiations with African partners they have to go through official channels," said Aline Leboeuf, a researcher at the Institute Francais.
The challenge posed to French companies present in Africa is complex, but it is clear the privileges they used to enjoy are being eroded.
A 2013 Gabon oil licensing round doled out 18 blocks to companies from around the world, but French oil major Total, Elf's successor following a merger, was left empty-handed. The following year, Gabon ordered Total to pay $805 million in back taxes, which the company said was an unfounded tax adjustment.
Total declined to comment for this story.
Other sectors that similarly rely on good relations with African governments - like telecoms and mining, in which companies like Orange and Areva respectively operate - could also be vulnerable.
Orange declined to comment.
A spokesman for Areva said the company would "continue to invest in exploration and innovation to find new deposits," but did not address the question of Africa risks.
Some officials and companies say the impact of the end of La Francafrique should not be overstated, since globalisation has been opening the field to competition anyway.
Ali Bongo, who has lived in Los Angeles and had a son in elite English boarding school Eton, made a point of trying to expand ties beyond the Francophone world.
France, meanwhile, has been diversifying its own ties.
In a shift from the past, it is increasingly seeking opportunities in former British colonies like Kenya and Botswana; the French government's Africa department now has more experts in east Africa than west, according to government sources. A month ago, Total won a production licence in Uganda.
"France has accepted the fact that ... it has a lot less ability to influence local politics," said historian Nathaniel Powell, who specialises in French-African relations, adding that it used to be a condition of working with an African leader that he would not allow in American companies.
"They used to pretty much own the Gabonese economy," he said. "Now African elites have much more leverage, because they have the Chinese, they have other options."
(Additional reporting by John Irish, Marine Pennetier, Richard Lough and Geert De Clercq in Paris; Editing by Pravin Char)