Sarkozy said in a column in French daily Le Figaro that publication of excerpts of his private conversations – which appear to implicate him in attempts to pervert the course of justice – were politically motivated. He also refuted several other corruption allegations.
"I think it is now my duty to break… (my) silence. If I do this, it is because the sacred principles of our Republic are trampled on with unheard of violence and with an unprecedented absence of qualms," the 59-year-old wrote in the Le Figaro daily.
Sarkozy has been implicated in a series of corruption cases, culminating with revelations in the press this month that he allegedly attempted to pervert the course of justice — information reportedly gleaned from excerpts of tapped phone conversations with his lawyer.
"Who handed over these documents when no lawyer has access to the procedure? The only people who hold (the documents) are judges or policemen…Are they above laws and judicial secrecy?" he asked.
The former president slammed the tapping of his phones by judges, compating them to the Stasi, the old East German secret police.
"These days, anyone who calls me should know that they will be listened to," he wrote. "This is not an excerpt from the wonderful film The Lives of Others about East Germany and the activities of the Stasi.
"It is not the actions of a dictator somewhere in the world at his opponents place. This is France, " is moved Nicolas Sarkozy.
The former president had been left fighting for his political life but it was the former president's lawyer who was the first to mount a fightback in the phone-tap scandal on Thursday.
Sarkozy's hopes of winning the 2017 presidential election are widely seen as having been seriously compromised, if not wrecked, by the publication of details of secret conversations between him and his lawyer, Thierry Herzog.
Excerpts published by news website Mediapart appear to implicate Sarkozy and Herzog in an attempt to pervert the course of justice in connection with a series of overlapping corruption investigations.
Herzog insisted Thursday that the "truncated" transcripts provided no evidence of wrongdoing and said he would file a legal complaint over the leaks, which, he suggested, could have been the work of current President Francois Hollande.
"I will be asking the prosecutor of the republic, via a formal complaint, to order an investigation aimed at identifying the authors of these violations of judicial secrecy," Herzog said.
"I think he should be able to find them very easily."
Mediapart's report followed similar but less detailed revelations in Le Monde. Herzog said it was no coincidence that Mediapart's founder and Hollande shared a lawyer, or that the president had received the two Le Monde journalists following publication of their report.
"The facts would seem to speak for themselves," Herzog said.
A serious crime
The recorded conversations suggest Sarkozy, 59, got a friendly judge to try to influence the outcome of legal deliberations in one of France's highest courts; had a mole in a senior position who tipped him off about a planned police raid on his offices; and was contemptuous of the judges investigating him – Herzog describing them as "bastards" in one conversation.
Such interference in the judicial process is regarded as "influence peddling" in French law and carries a maximum prison sentence of 10 years.
But there are also misgivings within the legal establishment about how the evidence against Sarkozy emerged.
A delegation of lawyers visited Hollande Thursday to express concern over an advocate-client conversation being recorded without any prior evidence of prima facie wrongdoing by the lawyer.
Herzog meanwhile denied that his "bastards" comment was incriminating.
"You should not read too much into a private conversation where I allow myself to let go a little," he said. "Have you never said things on the phone that go beyond what you actually think?"
Sarkozy is not currently charged with any offence in any of the various investigations, which are all linked to his election campaigns and their financing.