Vincent Bolloré, one of the most famous names in French maritime transport, has been taken in for questions by anti-corruption police near Paris.
The police are believed to have questioned the billionaire about his business dealings in Africa.
The Bolloré Group has denied any irregularities.
Prosecutors believe a Bolloré subsidiary helped two African presidents win power in return for lucrative contracts. Two rival businesses took the group to court over the concessions.
Investigators are looking into allegations that his Havas advertising agency provided discounted communications advice to Guinean President Alpha Condé and Togolese President Faure Gnassingbé at election time in return for the Bolloré Africa Logistics company being given licences to operate container ports in Conakry and Lomé.