Claude Gueant, interior minister at the end of Sarkozy's presidency, called the charges of Ziad Takieddine "absolutely ridiculous, absolutely without foundation," Radio France Internationale reported Wednesday.
Takieddine, a French-Lebanese business made the charges Friday after police searched his home looking for documents related to the claims.
Police were investigating a complaint by Sarkozy that investigative news site Mediapart had used falsified documents in a 2012 report in which it published a document in which a former Libyan dignitary purportedly said Libyan leader Moammar Gadhafi agreed to give Sarkozy's campaign $65.2 million.
Takieddine said proof of his claim existed but he would not reveal it because he did not trust the justice system.
The businessman said four people who did not live in France had proof Gadhafi financed Sarkozy's 2007 campaign.
Takieddine is under investigation for an alleged role in organizing and transmitting kickbacks for multimillion-dollar arms sales to Saudi Arabia and Pakistan between 1993 and 1995.