Mr Kouchner announced in parliament that he had never done anything illegal and had never used his public role for his own private gain.
The claims against him cover the period when he was a private consultant on health policy, before he was given the ministerial role.
Mr Pean maintains that two consultancies run by associates of Mr Kouchner received nearly $6m (£4.1m; 4.7m euros) from the governments of Gabon and Congo for reports that Kouchner had written.
And further, Pean claims that some of this money was paid after Mr Kouchner became French foreign minister in May 2007.
On Wednesday in the Nouvel Observateur, Mr Kouchner denied anything illegal or underhand had taken place and he was quoted as saying: "I never signed a contract with an African state."
