The National Prosecuting Authority (NPA) will "probably" furnish the public with its reasons once it had made a decision on whether to charge Jacob Zuma or not.

Amid heated speculation that a de facto decision to let Zuma, the ANC president, off the hook on 16 charges of corruption, fraud and racketeering, the Deputy Director of Public Prosecutions Willie Hofmeyr again stated emphatically last night that no such decision had been made.

His boss, advocate Mokotedi Mpshe said last week that Friday was D-day for him to start applying his mind to submissions made by Zuma's legal team which is said to include taped recordings of telephone conversations between former president Thabo Mbeki and the former head of the Scorpions, Leonard McCarthy, allegedly proving a conspiracy to keep Zuma from taking power.

DA leader Helen Zille on Thursday also made a submission to Mpshe arguing that a decision to drop the charges against Zuma would be a "body blow" to democracy and would create a "cascading effect" of impunity in political circles.

Zille demanded that the NPA disclose publicly its reasons should it decide the evidence presented to it by Zuma's team was so compelling that the charges should be dropped.

"The case against Mr Zuma has major legal implications for South African society who would be entitled to know the reasons for the withdrawal of charges," she said.

Sources had told the Cape Argus it was virtually a foregone conclusion that the charges against Zuma would be stayed.

Hofmeyr said he was not prepared to comment on suggestions by several sources that he and a fellow investigator had listened to the "spy tapes" in Zuma's lawyer Michael Hulley's Durban office.

Asked whether he had travelled to Durban to listen to the recordings, Hofmeyr said all the suggestions in the public domain, including leaks about Zuma's secret submissions, should be treated "with extreme caution" and intimated that much of the media speculation was not true.

Hofmeyr is said to have taken the lead in the NPA's discussions with Zuma's lawyers in their attempt to have the charges stayed.

The tapes allegedly "prove" Mbeki and McCarthy were in a cosy relationship and that under the former Mbeki administration there was executive interference in the Scorpions' work, resulting in selective prosecutions.

The alleged recording - of a conversation said to show McCarthy pledging allegiance to Mbeki - is among the tapes in Hulley's possession and were not, as previously understood, submitted to the NPA.

McCarthy, who did not respond to calls and emails for comment, is alleged to have told Mbeki "that you will always be my president", which has been interpreted by those in the Zuma camp as proof of a cosy relationship with the head of state.

Two other public figures allegedly recorded by state agencies, former NDPP Bulelani Ngcuka and businessman Saki Macozoma, on Thursday questioned the legality of the recording finding its way into submissions in a criminal case. Ngcuka said he was taking legal advice on the matter.

Inspector-general of Intelligence, Zolile Ngcakani, said on Thursday he had not received any complaints about the alleged recordings, but expressed concern.

"It is through recent media reports that I have become aware of the alleged monitoring and interception of specific telephonic conversations reported, which is of concern.

"These allegations however remain unconfirmed and are under consideration."

• This article was originally published on page 5 of The Cape Argus on March 27, 2009