The national director of public prosecutions, Bulelani Ngcuka, was warned on Thursday that he might be committing an offence by refusing to answer questions before the Hefer Commission.

Ngcuka refused to confirm or deny what he had allegedly said at an off-the-record briefing he had hosted in July with a group of editors.

He maintained that he would not break the confidentiality agreement between him and the editors about the contents of that meeting.

He further argued that he did not have to reveal the information because it was in large part about continuing investigations by his Scorpions unit, and therefore sub judice.

Judge Joos Hefer told Ngcuka that he might be committing an offence if he did not have a just excuse for refusing to answer questions put to him by advocate Steven Joseph. (Joseph acted for Ngcuka's main accusers, Mac Maharaj and Mo Shaik.)

The Commissions Act obliges witnesses before judicial commissions to answer questions put to them unless they had a just excuse not to.

Hefer nevertheless refused to force Ngcuka on Thursday to answer, saying he did not have the power to do so. A court had to decide whether Ngcuka's excuse was just after he had been prosecuted for the alleged offence, Hefer explained.

Former City Press editor Vusi Mona earlier submitted to the commission his version of the off-the-record meeting, which he also attended.

In it Mona alleged that Ngcuka made racist remarks and violated people's constitutional rights by revealing private information about them.

Ngcuka described Mona's version on Thursday as full of distortions and inaccuracies. He denied the accusation that he described Maharaj at the meeting "a straight-faced liar".

He already denied during his testimony-in-chief on Wednesday that he made racist remarks or violated the Constitution - Sapa