Mr Katsav made a lengthy televised speech, flanked by his wife Gila
Israel's former President Moshe Katsav told a televised news conference that he is a "victim of a lynching" over charges of rape and sexual assault.
The justice ministry - which on Sunday said it would indict Mr Katsav - called his speech pathetic and accused him of turning his case into a "media circus".
Mr Katsav's media advisors have also resigned in the wake of the lengthy TV appearance on Thursday evening.
He resigned in 2007 after four women accused him of rape and other crimes.
Speaking at a press conference in his hometown of Kyriat Malachi, flanked by his wife Gila, Mr Katsav vowed to prove his innocence.
"I am the victim of a lynching organised by the judicial counsellor of the government [Menahem] Mazouz, the police, politicians and the media," Mr Katsav said.
"My honour, and that of my family, has been attacked for the past three years. I have been humiliated, crushed, knocked down, and I suffer. But I am determined to fight to ensure that the truth emerges, all the truth, because I am innocent."
But a spokesman for Israel's justice ministry fired back after Mr Katsav's press conference.
Israeli daily Yedioth Ahronoth quoted Moshe Cohen as accusing the former Israeli president of turning the case into a "media circus," adding that it demonstrated that Mr Katsav had "taken a leave of his senses".
"The entire speech was riddled with bogus facts and false accusations, not to mention relentless slander against the attorney general and the heads of the law enforcement system," he added.
Israeli justice officials have not said when the indictment will be formally filed.
The charges relate to accusations by a number of women employees who worked for Mr Katsav while he was tourism minister and president.
If convicted of rape charges, Mr Katsav can face up to 16 years in jail. He would become Israel's first head of state convicted of sex offences.