Nicolas Sarkozy, former French president, has said France's legal system is being used for political means, after he was placed under formal investigation on suspicions of "influence peddling".
The step, which often but not always leads to trial, is a major setback to Sarkozy's hopes of a comeback after his 2012
defeat by Socialist rival Francois Hollande.
Sarkozy, 59, a conservative politician, denied on Wednesday wrongdoing in a number of investigations where his direct or indirect implication has cast doubt on his viability as a candidate in the 2017 election.
"I say to all those who are listening or watching that I have never betrayed them and have never committed an act against the Republic's principles and the rule of law," Sarkozy says according to extracts of his first interview since losing the 2012 election, which were aired on Europe 1 radio later on Wednesday.
"The situation is sufficiently serious to tell the French people where we stand on the political exploitation of part of the legal system today."
Sarkozy was questioned by investigators for 15 hours at their offices in Nanterre, west of Paris, on Tuesday.
He was interrogated over suspicions he used his influence to secure leaked details of an inquiry into alleged irregularities in his 2007 election.
The investigators are seeking to establish if Sarkozy, with the help of his lawyer Thierry Herzog, attempted to pervert the course of justice.
They suspect Sarkozy sought to obtain inside information from one of the magistrates about the progress of another investigation, and that he was tipped off that his mobile phone had been tapped by judges looking into the alleged financing of his 2007 election campaign by former Libyan leader Muammar Gaddafi.
'Stuffed with cash'
Sarkozy is alleged to have been helped to victory in 2007 with up to $70 million provided by Gaddafi, and envelopes stuffed with cash from France's richest woman, L'Oreal heiress Liliane Bettencourt.
He dismissed the Gaddafi claims as ridiculous and was cleared last year of taking Bettencourt's money when she was too frail to know what she was doing.
His campaign treasurer is one of 10 people awaiting trial in that case.
|Sarkozy charged with illegal fundraising
The Gaddafi investigation is ongoing. It was in connection with it that the judges last year obtained the unprecedented authorisation to tap the phones of a former president.
After four fruitless months, they discovered that Sarkozy had a secret phone registered under an assumed name, and it was conversations with his lawyer Herzog, recorded on that device, which triggered the investigation.
Leaked excerpts suggest that Sarkozy got a friendly judge to try to influence the outcome of confidential legal deliberations related to the Bettencourt case in return for his support for helping the judge to secure a lucrative post in Monaco.
They also imply he had a mole in a senior position who tipped him off about a planned police raid on his offices.
Such interference in the judicial process is regarded as "influence peddling" in French law and carries a maximum prison sentence of 10 years.
Sarkozy has recently been linked to a scandal over the funding of his campaign for re-election in 2012, and implicated in a number of other scandals which are still being investigated.
The most serious of these centres on an allegation that he helped organise kickbacks from a Pakistani arms deal to finance the 1995 presidential campaign of former premier Edouard Balladur.
He is also being investigated over allegations that while president, he used public funds to pay for party political research and handed out contracts for polling to a political crony.