Former French President Nicolas Sarkozy was reportedly placed in custody Tuesday as part of an investigation regarding illegal funding for his 2007 presidential campaign from former Libyan leader Muammar Qaddafi.

Sarkozy was being held at Nanterre police station, west of Paris, a judicial source told The Associated Press.

The investigation has been ongoing since 2013, but didn’t gain momentum until 2016 when Lebanese businessman Ziad Takieddine told Mediapart, an online investigative site, that he handed over suitcases of $6.2 million in cash to Sarkozy and his former chief of staff Claude Gueant on three occasions.

Takieddine – who has a history with the French justice system over allegations of providing illegal campaign funds in the past -- said he received the money from Qaddafi's intelligence chief in 2006 and 2007 and that the deliveries took place in the Interior Ministry, while Sarkozy was interior minister.

Investigators are looking into whether Sarkozy secretly received $61.6 million in total for his 2007 campaign from Qaddafi's regime – which would be more than twice the legal funding for the campaign at the time.

The alleged payments would also be in violation of French rules against foreign financing and declaring the source of campaign funds.

Both Sarkozy and Gueant have denied any wrongdoing.

Sarkozy and Qaddafi have had an interesting dynamic in the past, as the former French president welcomed the Libyan leader to France for a state visit, before placing France at the forefront of NATO-led strikes against Qaddafi's troops that helped rebel fighters topple his regime in 2011.

The Associated Press contributed to this report.