"I put it to you that you are a disgrace to your profession" were the last words addressed to former editor of City Press Vusi Mona on Friday by a member of the Hefer Commission.

"You are entitled to your opinion," Mona replied to senior counsel Marumo Moerane, representing National Director of Public Prosecutions Bulelani Ngcuka.

But this rejoinder was delivered without spirit and in a small voice. Mona had just spent two days being verbally torn apart by Moerane, senior counsel Norman Arendse (appearing for Minister of Justice Penuell Maduna) and especially by commission evidence leader Kessie Naidu.

Mona conceded that he had behaved recklessly and had given incorrect evidence to the commission. He admitted that he had "not applied his mind" to the possibility that ex-journalist Rajeni Munusamy and others, who had given him the information on which a story about Ngcuka had been based, may have had their "own agendas".

Mona began testifying on Wednesday before the commission, which is investigating accusations that Ngcuka was an apartheid-era spy and had abused his office as a result.

Mona came to give evidence, primarily about an off-the-record briefing held by Ngcuka for six black editors at the beginning of September. During the briefing, Ngcuka had, according to Mona, made a racist remark about Indians and had divulged defamatory information about people. In Mona's view, this behaviour constituted an abuse of power on Ngcuka's part.

This was the reason he decided to divulge what had taken place at the briefing, Mona said. But Naidu made him concede that he had "recklessly" handled the original story alleging that Ngcuka had been investigated as a spy by not checking information and allowing publication of a sub-heading that stated that Ngcuka was a spy.

Naidu also said that City Press's use, in another story, of the sentence: "Ngcuka was able to get a passport from the apartheid police even though he was convicted of high treason", showed bias against Ngcuka on the part of Mona because it was untrue - Ngcuka was never convicted of treason.

Mona began Friday's testimony by saying he wanted "to apologise unreservedly to Ngcuka, his family and to the National Directorate of Public Prosecutions for the pain the (original spy) story caused. I still regard Ngcuka as a man who can do his work."

But the relentless grilling of Mona continued, with Naidu asking why Mona had waited months before making the contents of the briefing public. Naidu also pointed out that two documents in which the contents of the off-the-record briefing had been published, and one of which was an "anonymous" e-mail attack on Ngcuka, contained exact turns of phrase and the same chronology of events as recorded by Mona in his own notebook.

Mona said the documents could have been written and distributed by a PR with whom he had discussed the meeting.

Naidu did not accept this answer. Mona then conceded that he knew that the PR agent, Dominic Ncele, had also been acting for the Kebble family and soccer boss Irwin Khoza - both of whom had been subjects of a Scorpions investigation.

With acknowledgements to Jeremy Gordin, Estelle Ellis and The Independent on Saturday.