Barricades have been set up in Port Gentil's main roads by protesters
French oil firm Total has evacuated its expatriate staff from Gabon's second city as clashes continue following the release of poll results on Thursday.
Two people have died in the violence, much of which has been aimed at French interests in Port Gentil.
Protesters accuse the former colonial power of helping fix the election of Ali Bongo as president - allegations denied by the French government.
His father died in June after ruling the oil-rich nation for 41 years.
Reports from the industrial city of Port Gentil say demonstrators have attacked public buildings, and sports and social clubs belonging to Total.
Looting continued in the city through Friday night, despite a curfew.
France has about 1,000 troops in the country.
A Total spokeswoman in Paris said it employees were being moved to the capital, Libreville, for their safety.
ALI BEN BONGO
Born in 1959 in Brazzaville, his mother is Gabonese singer and musician Patience Dabany
Studied at Sorbonne in Paris before entering politics in 1981
Became foreign affairs minister in 1989 - forced to quit in 1991 because he was too young
Organised pop-star Michael Jackson's visit to Gabon in 1992
Served as defence minister 1999-2009
Source: Ali Ben Bongo's website
Correspondents say Libreville has experienced less violence, but has a larger security presence.
Despite the unrest, a football World Cup-qualifying match between Gabon and Cameroon has been allowed to go ahead in the capital.
It was originally postponed in June following the death of Omar Bongo.
An estimated 20,000 people are at the stadium where expectations are high as Gabon has a chance of qualifying for World Cup for the first time.
There are fears that if Gabon loses the match it will trigger more violence.
According to the Associated Press news agency, the president-elect, a passionate football fan, has gone to the stadium to watch the game.
On Friday, the Constitutional Court confirmed his election despite the controversy surrounding the announcement of the results.
They were delayed amid a misunderstanding between election officials over how to verify the votes.
All three of the main candidates declared victory following Sunday's poll, while another candidate had been on hunger strike to protest against what he saw as irregularities in the election process.
Gabon is sub-Saharan Africa's fourth biggest oil producer and Africa's second biggest wood exporter, although most of its 1.4 million people live in poverty.
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