FORMER French President Nicolas Sarkozy made his first public comments today over allegations he duped the country's richest woman to raise election funds.
He also said that he had never betrayed his public duties and pledging to clear his name.
Sarkozy was placed under investigation last week for allegedly exploiting the mental frailty of 90-year-old L'Oreal heiress Liliane Bettencourt, after she was declared in a state of dementia, to help raise money for his 2007 election campaign. His lawyer rejected the case as flawed.
The "abuse of weakness" case threatens to torpedo any political comeback for Sarkozy, who lost a re-election bid in 2012 to Socialist Francois Hollande and has since avoided intervening directly in political life.
The conservative ex-president took to Facebook to thank those who had shown him support "at a time when I must face up to the ordeal of an unfair and unfounded investigation".
"To all of those who have supported me, and all of those who have fought against me, I want to affirm that at no point in my public life have I betrayed the duties of my position," he wrote.
The 58-year-old, a lawyer by training, said he would seek no special treatment as he fought the case being brought by a Bordeaux magistrate.
"I will devote all of my energy to prove my probity and honesty," he wrote in a message signed by the initials NS. "The truth will prevail eventually. I have no doubt about it."
Bettencourt was declared in a state of dementia in 2006 and was placed under the guardianship of her family in 2011.
A public prosecutor said on Thursday that Sarkozy was being investigated "for taking advantage of a vulnerable person in February 2007 and during 2007 to the detriment of Liliane Bettencourt", a crime punishable by up to three years in jail.
Sarkozy has been placed under formal investigation, which is the final step before a suspect is accused of a crime and drawn into a case which could take years to complete.
His lawyer, Thierry Herzog, said he would seek to get the case thrown out, arguing that investigating magistrate Jean-Michel Gentil was more interested in gathering incriminating evidence against Sarkozy than hearing both sides of the story.
The former president has also enjoyed vocal support from centre-right political allies, including former speechwriter and Elysee first secretary Henri Guaino, who have taken to television and radio to defend his reputation.
His former industry minister Christian Estrosi suggested the timing of the investigation was politically motivated to distract attention from a scandal surrounding one of Hollande's ministers.
Sarkozy has repeatedly hinted that he could make another bid for the presidency in 2017, a prospect supported by his continuing popularity among conservative voters and Hollande's low approval ratings.