A recording of an alleged telephone call between then President Thabo Mbeki and former Scorpions boss Leonard McCarthy - in which the latter is said to have pledged allegiance of sorts - is among the tapes in the sole possession of Jacob Zuma's Durban lawyer, Michael Hulley.

It is understood that the NPA was not given copies of the so-called spy tapes, which forms part of Zuma's latest bid to have the prosecution drop charges against him,

Deputy director of public prosecutions, Willie Hofmeyr - who is the key liaison with the Zuma legal team on behalf of the State - was allowed, along with a colleague, to listen to the recordings in Hulley's Durban office.

The Zuma legal team is using the alleged recordings to prove the ANC's president's claims of a political conspiracy behind his prosecution for fraud, corruption and racketeering.

The recordings, allegedly made by state intelligence agencies, are said to show that under the Mbeki administration there was executive interference in the Scorpions' work, which resulted in selective prosecutions.

Former prosecutions boss, Bulelani Ngcuka, and husband to then deputy president Phumzile Mlambo-Ngcuka, is said to feature prominently in the conversations with McCarthy.

Ngcuka, in a statement to the media on Tuesday, said he was considering legal action, given that he believed the recordings were unlawfully obtained and that their possession was also illegal.

McCarthy, who did not respond to calls and e-mails 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.

The conversation is alleged to have occurred at the time that McCarthy sought approval from the South African government for a plum post at the World Bank's anti-corruption unit.

Eyebrows were raised last year at the time of McCarthy's appointment, given Parliament's endorsement of its joint standing committee of intelligence's report on the so-called special mole browse report.

That report had urged the executive to take action against McCarthy for his role in the so-called intelligence gathering exercise by the Scorpions, widely viewed as an attempt to discredit Zuma.

Hofmeyr said last night that he was not prepared to comment on claims that he had listened to the tapes in Hulley's office.

Asked whether he had travelled to Durban to do so, Hofmeyr said all the suggestions floating in the public domain about Zuma's latest submission to the NPA should be treated "with extreme caution". He implied that much of the media speculation was untrue.

Mbeki last night broke his silence on claims that Zuma accused him of political conspiracy and improper involvement in the arms deal to persuade his prosecutors to drop the corruption case against him.

In a statement, Mbeki's office said: "Former president Mbeki wishes to invite anyone who has such evidence to hand it over to the law enforcement agencies so that legal remedies are sought by any party that believes that it may have been unduly compromised," Mbeki's office stated late yesterday.