Deputy President Jacob Zuma will not be prosecuted over South Africa's multi-billion rand arms deal, despite indications that there may be a corruption case for him to answer to, the country's top prosecutor said on Saturday.

The decision was taken in spite of a recommendation by the investigating team that Zuma be criminally charged, national director of public prosecutions Bulelani Ngcuka said.

"We have concluded that, whilst there is a prima facie case of corruption against the deputy president, our prospects of success are not strong enough," he told reporters in Pretoria.

'We can't prosecute if it is not sufficiently winnable'

"That means that we are not sure if we have a winnable case. Accordingly, we have decided not to prosecute the deputy president."

The decision could be reviewed should new evidence arise.

The prosecuting authority probed claims for the past two years of corruption flowing from the Nkobi Group's acquisition of shareholding in African Defence Systems (ADS), and Zuma's role therein.

Zuma's financial advisor, Schabir Shaik, was a director of the Nkobi group of companies, which had shares in the French arms company Thomson CSF. Thomson, in turn, had shares in ADS.

The deputy president has repeatedly rejected allegations that he tried to solicit a R500 000 bribe from the former Southern African head of Thomson CSF, Alain Thetard.

'This is not the time for point-scoring'

Justice Minister Penuell Maduna said he would not speculate on the effect the affair might have on Zuma's political career.

"The fact is he is not going to be prosecuted, at least not for now..."

Ngcuka announced that Shaik would be charged with corruption, fraud, theft of company assets, tax evasion and reckless trading. He was expected to appear in the Durban Magistrate's Court on Monday.

The Nkobi group and Thomson CSF would be prosecuted for contraventions of the Companies Act. Evidence against Thetard and Thomson would be referred to the French authorities.

Ngcuka said national interest demanded that facts were "unassailable" before a criminal prosecution was instituted.

"In a case of this nature, we can't prosecute if it is not sufficiently winnable," he said.

"At the same time, given the public interest in the matter, we cannot continue with a prolonged investigation that casts a shadow over the deputy president of the country, whilst we are not sure of the outcome."

Issues around the declaration of gifts and donations received by Zuma would be referred to Parliament for consideration.

The manner in which the matter has been handled left much to be desired, Ngcuka said. However, he would not rush into a prosecution simply to prove a point.

"This is not the time for point-scoring. I have to put the interests of the country above personal displeasure."

The matter has resulted in much tension between Zuma and the prosecuting authority in recent weeks. Zuma claimed leaks of information apparently from the unit were "designed to cast aspersions on my integrity".

A Sunday newspaper recently published a list of questions compiled by investigators and sent to Zuma.

Ngcuka denied the leak came from the authority, saying the questions were also given to Zuma's lawyers "and they know best what they did with them".

He added the probe was conducted without undue influence from the government.

The investigation was one of the most difficult yet undertaken by the authority, and was only launched only after careful consideration of the implications, Ngcuka said.

After receiving information from a whistle-blower and evidence from an auditing firm, "we were satisfied that we had a reasonable suspicion and thus no choice but to continue".

The investigation was conducted in such a way that Zuma's identity was not revealed, Ngcuka said.

Maduna received a report on the investigation from Ngcuka.

Zuma's spokesperson was not immediately available for comment.

With acknowledgements to Mariette le Roux, Sapa and The Star.