The Democratic Alliance (DA) has called on Inspector General of Intelligence Zola Ngcakani to investigate allegations that former president Thabo Mbeki's phone was tapped during his time in office.

Media reports suggesting state intelligence agencies had recorded calls between Mbeki and, among others, the former head of the Scorpions, Leonard McCarthy, were troubling, DA Chief Whip Ian Davidson said in a statement on Friday.

"If this is the case, then the intelligence community appears to be responsible for illegally tapping the phone conversations of a sitting president - a quite outrageous state of affairs that warrants an urgent investigation.

"It is essential that this investigation uncovers not only the source of these phone recordings, but also how they have now allegedly ended up in the hands of Mr Jacob Zuma's lawyer," he said.

Media reports earlier this week claim the latest representations made to the National Prosecuting Authority (NPA) by Zuma's legal team, in a bid to have corruption charges against him withdrawn, include tapes of phone conversations in which Mbeki and other prominent people discuss the case against his political rival.

On Friday, a report in the Mail & Guardian newspaper said it was likely Mbeki's phone was not actually tapped, but rather that the tapes feature references by senior officials to him and his thoughts on the case.

The newspaper said the NPA was locked in an internal battle over whether to proceed with the politically-fraught case against the African National Congress (ANC) leader and presidential frontrunner, despite the potentially damaging tapes.

Mbeki's spokesperson has reiterated that the former president did not interfere in the Zuma case, and said he did not know whether his phone was tapped.