Deputy President Jacob Zuma has accused the National Directorate of Public Prosecutions of finding him guilty of corruption linked to the country's arms deal without having the necessary evidence.

"No matter what the NDPP says, there can only be one reason I am not being charged; there is no case against me. I know this, and so does the NDPP," Zuma said on Sunday.

Ngcuka announced on Saturday that Zuma would not be prosecuted, despite indications that there may be a corruption case for him to answer to. The decision was taken in spite of a recommendation by the investigating team that Zuma be criminally charged.

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

Zuma has repeatedly rejected allegations that he tried to solicit a R500 000 bribe from Alain Thetard, the former southern African head of French arms company Thomson CSF.

The Scorpions has 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 Thomson CSF. Thomson, in turn, had shares in ADS.

The decision not to prosecute could be reviewed should new evidence arise.

Zuma said on Sunday Ngcuka's statement was equivalent to a judgement against him, after a long trial by media.

"The purpose of the latest public announcement is to leave a cloud hanging over my integrity. The hallowed principle of presumption of innocence until proven guilty has been completely ignored."

He said he had always questioned the methods and length of time the probe had taken, and had called upon investigators to take him to court if they believed that had a case against him.

"I now question the manner in which the investigation has been 'concluded'."

He said he had serious reservations about the public utterances made on Saturday. The NDPP had produced a statement that contained serious innuendoes.

"He (Ngcuka) has declined to prosecute, indicating that they accept that there is no case to answer.

"At the same time, the country has been told by the National Director that there is a prima facie case of corruption against me, based on circumstantial evidence."

Zuma said Ngcuka had admitted that the alleged evidence related to correspondence about him.

"None of it was written by me, received by me or addressed to me. The investigation was apparently initiated after receipt of an encrypted fax, which originated in French and was translated into English. I have never seen the French version of the alleged fax and do not know whether it really exists."

Zuma said his lawyers had asked public prosecutions in a letter on August 7 for handwritten and typed copies of the original French documents. They were not provided.

As a result, once again, his lawyers had to invoke the Promotion of Access to Information Act, and to date there has been no response.

"I am forced to continue to question the real motives of the investigation and the manner of its conclusion by the NDPP."

"The Minister of Justice also appeared on national television on Saturday 23 August, and told the nation it was a "sad moment" that the investigators have concluded that I have a case to answer. What is this case? Where should I answer it?"

He said he intended taking the matter further and would consult with his lawyers.

There was mixed political reaction to the decision not to prosecute Zuma, with most parties calling for his head.

With acknowledgements to Amy Musgrave, Moipone Malefane, Sapa and the Mail and Guardian.