Pressure is mounting on National Director of Public Prosecutions Bulelani Ngcuka's accusers to produce their "proof" of his being an apartheid-era spy before the Hefer Commission of Inquiry - or face subpoenas.

As the commission entered its second week - but only the third day of hearings - it became clear that neither evidence leader Kessie Naidu SC nor Marumo Moerane SC, counsel representing Ngcuka, were going to play Mr Nice Guy any longer.

Naidu asked commission secretary John Bacon to write a letter to former ANC intelligence operative Mo Shaik and former transport minister Mac Maharaj to supply the commission with documentation, purporting to prove that Ngcuka was a spy, which had been shown during television interviews.

This followed Moerane requesting - in the light of newspaper revelations about the identity of apartheid-era Agent RS452 - that the commission make it very clear what the documentary basis of the allegations against his client was.

As a result, Maharaj and Shaik may be faced with a subpoena to deliver the documents should they not comply with the demands in Bacon's letter.

Neither Maharaj nor Shaik attended the commission yesterday. Also absent was their attorney, Yunis Shaik. The only word from them was a message sent via Bacon that it was not their contention that Ngcuka - who made his first appearance at the commission hearings yesterday - was Agent RS452.

This followed an exposé in the Cape Times on Tuesday that Agent RS452 was a human rights lawyer, Vanessa Brereton. Last week the commission granted a special request that the cross-examination of witnesses be allowed.

It emerged that some of the documents that form the basis of the spy claims against Ngcuka are in the possession of the commission and will be made public.

Johannesburg attorney Patrick Maqubela testified that he had been only recently approached by an attorney representing Shaik and Maharaj and asked whether he knew of the role played by Ngcuka in Maqubela's arrest in the early 1980s.

This information was clearly solicited from Maqubela by Naidu, to prove that Maharaj and Shaik are still seeking back-up information for their allegations.

Maqubela was tried and sentenced for high treason in the Pietermaritzburg High Court. During the trial Ngcuka refused to give evidence against him, for which he was sentenced to three years' imprisonment.

During Maqubela's cross-examination by Moerane, Maqubela agreed with counsel that there was a strange correlation of circumstance and time in the making of the allegations against Ngcuka. The allegations coincided with the Scorpions investigating Maharaj for corruption and Shaik's brother Schabir being charged with several crimes, including corruption and tax evasion relating to the country's multi-billion rand arms deal.

The Hefer commission, chaired by retired acting chief justice Joos Hefer, was set up last month to investigate claims that Ngcuka was a spy for the apartheid government. Later the terms of reference for the commission were extended to include a probe into allegations that Ngcuka and the Minister of Justice Penuell Maduna were abusing the powers of the National Directorate of Public Prosecutions because of their alleged obligations to the apartheid regime.

Maqubela told the commission that he did not believe that either Ngcuka or Maduna had any obligations to the apartheid government, or would have abused their powers as a consequence of this.

Earlier in the proceedings Bacon said the commission had requested an affidavit from Brereton, the woman who has confessed to being Agent RS452.

Naidu asked Judge Hefer whether the commission had any thoughts of making itself vulnerable to the "inclement weather" of England so as to take evidence from Brereton, who now lives in London.

Today another ANC operative, Litha Jolobe, and Port Elizabeth advocate Glenn Goosen are expected to take the stand.

Tomorrow advocate George Bizos SC will make submissions to the commission on behalf of South Africa's intelligence agencies and the police.

Until now there have been unresolved discussions between the commission and these agencies, about the availability of documentation relating to the spy probe. It is believed that President Thabo Mbeki, as chief of all government agencies, could be called upon to intervene should the stand-off continue.

With acknowledgements to Estelle Ellis, Jeremy Gorkin and the Cape Times.