The minister announced through his counsel, advocate Norman Arendse, that he disbelieved allegations about remarks that Ngcuka was alleged to have made at an off-the-record meeting.
Arendse told the Hefer Commission at its public hearing in Bloemfontein that Maduna was shocked when he first heard the allegations.
"They were totally out of character." Arendse added that Ngcuka reported to his minister on the meeting after he had held it.
He was referring to what has now become a controversial briefing Ngcuka gave to a selected group of black editors on July 24.
The national director of public prosecutions called it shortly after an e-mail containing a range of allegations against him started circulating in the media.
Former City Press editor Vusi Mona, who also attended, has since lodged an official complaint against Ngcuka with the Public Protector.
Mona accused Ngcuka of making racist remarks at the meeting.
He further maintained that Ngcuka had violated people's constitutional rights by disclosing confidential information about their private matters.
Those Mona believed to have been violated included Deputy President Jacob Zuma, against whom Ngcuka's office has since established a "prima facie" corruption case.
When Ngcuka earlier announced this, Maduna also showed his meaningful support.
The minister was at his chief prosecutor's side when Ngcuka informed the media that he had nevertheless decided against charging Zuma because the chances of conviction were too slim.
Mona appeared to crumble under gruelling cross-examination yesterday.
He was grilled about his allegation that Ngcuka had abused his official powers at the July briefing.
He also had to repeatedly defend his stated motive for breaching the confidentiality convention of an off-the-record briefing.
Mona maintained that he felt it his "citizen's duty" to report Ngcuka two months after the meeting to the Public Prosecutor.
He denied that he was influenced by Ngcuka's announcement of the prima facie corruption case against Zuma.
Mona also denied that allegations against himself, as reported in the Star newspaper, prompted him to accuse Ngcuka.
The Star questioned Mona's ethics by alleging that he was involved with a communications company that won a Mpumalanga government contract.
Mona admitted eventually that he was for a few days under the wrong impression that Ngcuka's investigating unit, the Scorpions, were investigating him for this. This was later corrected.
Mona further conceded that he was reckless to allow publication of the first reports that revealed the spying allegations against Ngcuka and appeared in the City Press.
He denied that the reports were deliberate attempts to mislead the paper's readers.
He will face Ngcuka's counsel, Advocate Marumo Moerane, in cross-examination today.
Meanwhile, the SA National Editors' Forum (Sanef) yesterday issued a strongly worded statement against former City Press editor Vusi Mona for unprofessional conduct in relation to his appearance and evidence before the Hefer commission of inquiry.
Sanef accused Mona of breaching all the rules of professional conduct in attending a confidential briefing and then disclosing the content of the meeting.
Retired Appellate Judge Joos Hefer was appointed by President Thabo Mbeki to probe National Director of Public Prosecutions Bulelani Ngcuka's past and to determine whether Ngcuka was abusing his office to persecute apartheid-era opponents.
One of the incidents cited in support of the second charge is an off-the-record briefing by Ngcuka of a group of editors during, which he reportedly defamed several prominent persons and made racist comments.
"Mona, who has left his publication under a cloud concerning a serious conflict of interest, has compounded his earlier publication of the apparent minutes of the Ngcuka briefing.
"Unlike most of the media community who believe the media should not be involved in the Hefer commission, Mona has chosen to use the commission to repeat and enlarge upon his earlier breach of confidence," Sanef said.
The editor's body added that the principle of confidentiality of sources and information was regarded as sacrosanct by journalists, many of whom had gone to jail to uphold the principle.
Background and confidential briefings were common practice in journalism.
Editors were experienced in contexualising such briefings and retaining their own independence in regard to them, the association added.
"Mona may have had reasons for disquiet at what he says took place at the briefing, but the professional rules of journalistic conduct provide for an ethical standard of conduct to deal with such situations," Sanef said.
"If he did not accept the confidentiality of the briefing, he should have stated that at the time and left, but once he stayed after Ngcuka had stated it was a confidential briefing, he was in our view bound to abide by those terms.
"For him to remain at the briefing and then state later that he did not accept it was in confidence is a gross breach of professional ethics," Sanef charged.
"Sanef believes that in disclosing the contents of the briefing Mona has seriously discredited himself as a journalist.
Sanef will continue to promote ethical journalism amongst its members in order to maintain the public's trust in the media".
Sanef's national council last week resolved to develop detailed guidelines for journalists about professional participation in background and confidential briefings.
The council at the weekend also decided to distance itself from journalists and editors who breached their duty to keep confidences.
Sanef deputy-chairman Guy Berger yesterday night told Sapa Mona had been a member, albeit an inactive one. Berger said Mona's membership effectively terminated when he resigned from the City Press.
Asked whether the organisation would have acted against Mona if he had still been a member, Berger replied "yes". – Sapa.