South Africa's former corruption buster Willem Heath says he has not "switched sides" on the arms deal nor is there a conflict of interest.

But there are those who once confided in him who say he will be acting unethically by advising former deputy president Jacob Zuma on the merits of the corruption case against him.

Among them is arms contractor Richard Young, who is suing the government for R149 million after he lost out in the arms deal to ADS, a subsidiary of French arms company Thales.

Heath, who headed the Special Investigating Unit for six years, was approached at the time by MP Patricia de Lille to investigate allegations of corruption in the arms deal.

He was controversially excluded from a multi-agency probe, ostensibly after the Constitutional Court ruled a judge could not head the unit because of the separation of powers doctrine.

Heath's exclusion led to a heated dispute between parliament's public accounts committee, headed by the IFP's Gavin Woods, and Zuma in his capacity as leader of government business.

Heath later resigned as a judge and started his own consultancy. He was among the State witnesses in Schabir Shaik's corruption trial.

After meeting Zuma in Johannesburg yesterday, he said he would advise the former deputy president on the "merits of the case against him".

But his brief as legal counsel was qualified by the fact that he would not be part of the defence team that would represent Zuma in a criminal trial. He had been briefed as an advocate by an independent attorney, who was not a member of Zuma's defence team. If the State called him as a witness, he would give evidence as he had in the Shaik trial.

Young said last night: "It doesn't sound right to me. I've got a current case. I've met Heath and his (SIU) people on numerous occasions."

Young said his case involved ADS, owned by Thales and which had been represented by advocate Kessie Naidu in the Shaik trial. Naidu was now acting for Zuma and Heath had made it clear he would consult Zuma's legal team if necessary.

"He must withdraw or something will be done about it," said Young. "I have confided in Heath and his unit. Any involvement with anyone connected to Schabir Shaik, Chippy Shaik, Zuma and Thales is a massive conflict of interest."

Woods said the decision was "more than ironic or inconsistent", but Heath, arguing he had not "switched sides", says there is no conflict of interest and that Young "never consulted" the SIU *1.

He attended a meeting between Young and the the Auditor-General and visited him when he started his consultancy. Young had never indicated he would call him as a witness,*2 he said.

With acknowledgements to Angela Quintal and Cape Argus.

*1 This is not true. On advice, I first contacted the senior investigator of the SIU during May 2000. I then gave them a very detailed briefing some weeks later, as well as 5-lever arch files full of evidence relating to Thomson-CSF, ADS and Chippy Shaikh.

In November 2000 I met with all the investigators who were investigating the combat suite, including some from the SIU and gave them another detailed briefing, including original colour copies of the organigrams, drawn by myself with input from a consultant. The multifarious links on the organigrams were explained in detail. Not all of these links necessarily involve unlawfulness. But they were sensitive all the same.

These very same organigrams were held up just two months later by President Mbeki in his televised national address where he announced that the SIU would not be getting a presidential proclamation to investigate the SIU. Mbeki made accusations against Heath concerning these organigrams, including being in possession of them. Just where did Heath get them - from his investigators who got them from me.

Maybe I did not consult the SIU, they consulted me.

I also personally consulted him one-on-one in early August 2001. This was just after he had formed Heath Executive Consultancy, but was still based in East London. I have an idea that he was still winding down his affairs at the SIU.

*2 Through no fault of my own, the pleadings have only closed in my case during the last few weeks and we are still to strategise the details of the trial itself. We could well have called Heath as a witness.