Both center-right politicians on Monday said they would take legal action against Robert Bourgi, a lawyer who made the accusations over the weekend in Le Journal du Dimanche.
Bourgi alleges that presidents from former French colonies funded Chirac, Villepin and former National Front leader Jean Marie Le Pen between 1995 and 2005.
He said he made cash deliveries himself to Chirac's office while Chirac was mayor of Paris from 1977 to 1995.
Bourgi said that Villepin was an art collector and he received items of value such as African masks. Villepin told French television the claims were "false" and "outrageous".
Villepin may contest next year's elections against French president Nicolas Sarkozy, who is reported to be a close friend of Bourgi.
Meanwhile Karim Wade, the son of the Senagalese president, Abdoulaye Wade, has lodged a complaint against Bourgi for defamation.
Karim Wade was accused of giving 760,000 euro in election campaign funding to Villepin, when he was the French president's secretary general.