Paris(CNN) Former French President Nicolas Sarkozy says there is no evidence to support allegations he illegally accepted money from Libya to finance his 2007 election campaign.
"I am accused without any physical evidence," Sarkozy wrote in an opinion piece published Thursday in French Newspaper Le Figaro.
A source close to the case told CNN Wednesday that the 63-year-old had been placed under formal investigation for illicit campaign financing, passive bribery -- illegally receiving money -- and concealment of embezzlement of Libyan public funds.
Sarkozy has also been placed under judicial supervision, a step investigators in France can take to limit the movements of a suspect, according to the source. It's not clear what specific restrictions have been placed on Sarkozy.
The former French leader was summoned for questioning Tuesday, which he voluntarily attended, according to an official at the court.
The official, who did not want to be named, said Sarkozy was being investigated by anti-corruption authorities.
Sarkozy, leader of France from 2007 until 2012, has been dogged by accusations of financial wrongdoing.
In July 2012, shortly after he was ousted from office by the Socialist François Hollande, police raided Sarkozy's home as part of an investigation into alleged illegal assistance from L'Oréal heiress Liliane Bettencourt during the 2007 election campaign.
Those charges were eventually dropped in 2013, but another investigation was opened the following year, and in February 2017 a judge ordered Sarkozy to face trial.
That came after an embarrassing loss for the former President, as an attempt to return to frontline politics saw him finish third in the Republican party's presidential primary.
The winner of that race, François Fillon, was subsequently defeated by centrist candidate Emmanuel Macron, who eventually won the presidency after a runoff against National Front leader Marine Le Pen.