Nicolas Sarkozy is accused of accepting €50m from former Libyan leader Muammar Gaddafi's regime
Former French president Nicolas Sarkozy is being held in police custody over campaign financing, according to reports.
A Reuters court source says Mr Sarkozy is being questioned by police in connection to an investigation into "irregularities" in election campaign financing.
The investigation relates to alleged Libyan funding for his 2007 campaign, Le Monde newspaper reported.
He is said to have accepted €50m from Muammar Gaddafi's regime, claims which have been repeated by the late Libyan dictator's son and French businessman Ziad Takieddine.
Mr Sarkozy has repeatedly denied accepting money from Libya.
According to Le Monde, this is the first time Mr Sarkozy has been questioned in relation to this investigation, which was opened in April 2013.
He can be held for up to 48 hours and presented to the Magistrates Court for indictment straight away if police seek charges.
In March 2011, Saif al-Islam Gaddafi, the late dictator's son, told Euronews: "Sarkozy has to give back the money he accepted from Libya to finance his electoral campaign.”
“We financed his campaign and we have the proof,” he said.
"The first thing we're demanding is that this clown gives back the money to the Libyan people."
Mr Takieddine claims he delivered three suitcases stuffed with cash to Paris between 2006 and 2007.
Mr Sarkozy was president of France from 2007 until 2012.
He attempted to stage a comeback for the 2017 election, but failed to convince the voters in his own party to support him and had to concede to Francois Fillon and Alain Juppe.
Mr Sarkozy faced accusations of exploiting L'Oreal heiress Liliane Bettencourt, taking advantage of her "mental fragility" to seek a donation to his political party for the 2007 election, but the case against him was dropped.
His name has been linked to a number of allegations of misconduct since he left office - however, the majority have been dismissed or come to nothing.
Mr Sarkozy was last year ordered to stand trial in a separate investigation regarding the financing of his failed re-election bid in 2012.