Nicolas Sarkozy is facing new allegations that he received millions of euros in illegal financing from late Libyan dictator Muammar Gaddafi's regime.
Days before a crucial presidential primary, French-Lebanese businessman Ziad Takieddine said he delivered suitcases from Libya containing 5 million euros in cash to Mr Sarkozy and his former chief of staff.
In a video interview with investigative website Mediapart, Mr Takieddine described three alleged handovers in detail.
Mr Sarkozy has denied wrongdoing in the case, which involves funding for his winning 2007 presidential campaign. An investigation has been under way since 2013.
Investigators are examining claims that Gaddafi's regime secretly gave Mr Sarkozy 50 million euros overall for the 2007 campaign. Such a sum would be more than double the legal campaign funding limit at the time of 21 million euros, and the alleged payments would violate rules against foreign financing and declaring the sources of campaign funds.
Mr Sarkozy faces conservative rivals in a primary on Sunday as he seeks the presidency again after losing it in 2012 to Socialist Francois Hollande.
Polls suggest he and former prime minister Alain Juppe are the frontrunners for their conservative party, the Republicans.
In the Mediapart interview, Mr Takieddine said he was given 5 million euros in Tripoli by Gaddafi's intelligence chief on trips in late 2006 and 2007.
He said he gave the money in suitcases to Mr Sarkozy and Claude Gueant on three occasions. He said the handovers took place in the Interior Ministry, while Mr Sarkozy was interior minister and Mr Gueant was his chief of staff.
Mr Gueant has also denied wrongdoing.
Mr Sarkozy had a complex relationship with Gaddafi. Soon after becoming president, Mr Sarkozy invited the Libyan leader to France for a state visit and welcomed him with high honours, but Mr Sarkozy then put France in the forefront of Nato-led air strikes against Gaddafi's troops that helped rebel fighters topple his regime in 2011.
Mr Sarkozy faces other legal troubles, although nothing prevents him from seeking office while they are still under investigation.
Prosecutors notably want him and 13 others sent to trial for another campaign financing case, involving his failed 2012 presidential bid.