Billionaire French industrialist Vincent Bollore was held for a second day of questioning by anti-corruption police on Wednesday over allegations his company helped two African leaders win elections in return for lucrative contracts.

The 66-year-old head of the Bollore Group was taken into custody Tuesday in the Paris suburb of Nanterre as part of an investigation into how its African logistics subsidiary secured contracts to run Lome port in Togo and Conakry port in Guinea.

Prosecutors are looking into whether Bollore Group’s communications arm, Havas, undercharged Guinean President Alpha Conde and Togolese President Faure Gnassingbe for work on their campaigns as a sweetener for the contracts, Le Monde newspaper reported.