Ex-President Nicolas Sarkozy has said the French justice system is being used for "political ends" after he was placed under formal investigation for influence peddling.Follow @Graphicgh
In extracts released ahead of the broadcast of a TV interview, Mr Sarkozy denied committing any unlawful act.
He said the case against him was intended to harm his reputation.
It is alleged Mr Sarkozy sought insider information from a judge about an inquiry into illegal campaign funding.
Mr Sarkozy was detained on Tuesday for questioning - the first time a former French head of state has been held in police custody.
Mr Sarkozy has recorded an interview for TF1 television and Europe 1 radio for later on Wednesday evening.
In it he says: "The situation is sufficiently serious to tell the French people where we stand on the political exploitation of part of the legal system today.
"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."
Mr Sarkozy says he is "deeply shocked" by the investigation and accuses the Syndicat de la Magistrature trade union of seeking to destroy him.
"Everything is being done to give me a reputation that is not true," he says.
Mr Sarkozy says: "In our country, which is the country of human rights and the rule of law, there are things that are being organised.
"The French need to know what they are and, in conscience and freedom, judge what to make of it."
Mr Sarkozy was released from custody around midnight (22:00 GMT Tuesday) after appearing in court in Paris.
When a suspect is placed under formal investigation, he or she is then examined by a judge, who determines whether there is sufficient evidence for the suspect to be charged.
The step often, but not always, leads to trial. Influence-peddling can be punished by up to 10 years in prison and a fine of 150,000 euros (£120,000; $205,000).
Investigations into Sarkozy
July 2014: Placed under formal investigation on suspicion of peddling influence to obtain details from a magistrate about legal proceedings against him in 2013
October 2013: A criminal investigation into allegations he solicited secret campaign financing in 2007 from France's richest woman, Liliane Bettencourt, is dropped
April 2013: Judges open an inquiry into allegations that the Gaddafi regime helped finance his 2007 election campaign
February 2014: Named as a witness in investigation into funding for Edouard Balladur's unsuccessful presidential bid in 1995
A number of other inquiries are under way into wrongdoing by senior officials during his presidency, in which he has not figured directly
Investigators are trying to find out whether Mr Sarkozy, 59, who was president from 2007 to 2012, had promised a prestigious role in Monaco to senior prosecutor Gilbert Azibert in exchange for information about the investigation into illegal campaign funding.
Mr Azibert was never given the job.
The inquiry into funding is looking into whether Mr Sarkozy received illegal donations for the 2007 election campaign from late Libyan leader Muammar Gaddafi.
Mr Sarkozy is hoping to challenge again for the presidency in 2017 and the allegations are seen as a blow to his hopes of returning to office.
Mr Sarkozy's lawyer, Thierry Herzog, and Mr Azibert have also been placed under formal investigation.