The 63-year-old was being questioned over suspected irregularities in the financing of his successful campaign
The 63-year-old was being questioned over suspected irregularities in the financing of his successful bid for the presidency, an official in the French judiciary said.
The probe related to alleged Libyan funding for his 2007 campaign, Le Monde newspaper reported.
Sarkozy has previously denied the allegations.
Before he was killed during an uprising in 2011, Libya’s former dictator Muammar Gaddafi had claimed he gave millions to Mr Sarkozy’s first presidential campaign.
In January, French businessman Alexandre Djouhri, who was close to the former president, was released on bail after being arrested in London as part of the probe.
The 59-year-old was accused of being an intermediary in the alleged financing from Libya.
Mr Sarkozy’s time in and after office has been married by political and financial scandal, as he faced accusations of illegal campaign funding and corruption.
In July 2014, two years after leaving office, he was charged with corruption by French prosecutors.
Paris-born Mr Sarkozy was the leader of the Union for a Popular Movement political party when he was elected in May 2007.
He served as president until May 2012 when he was defeated by Socialist Party candidate Francois Hollande by a margin of just over three per cent.
Mr Sarkozy briefly retired from politics before returning in September 2014 and becoming leader of the Union for a Popular Movement again.
His bid to become president again failed when he was eliminated in the first round of voting in the French presidential primary in 2016.