National Prosecuting Authority acting chief Mokotedi Mpshe was not aware of any phone tapping or spy tapes reportedly linked to their investigation of ANC president Jacob Zuma.

"I'm not aware of the Scorpions tapping any phones. I saw it in the media but I've never seen a tape myself," said Mpshe on Friday.

He was speaking in Durban after a conference on human trafficking.

He said that the NPA was not investigating any intelligence member because there was "no wrong doing".

"We are just investigating the source of some information I have," he said. He was unable to elaborate on the "information".

He was responding to reports that tapped phone calls that included conversations of former president Thabo Mbeki and former prosecutions boss Bulelani Ngcuka were submitted during the private "representation" process to have fraud and corruption charges against Zuma dropped.

Both the NPA and Zuma's lawyers have opted to keep the details of the representations confidential. Although they relate to Zuma's prosecution, because they were not handed in a court, they do not have to be made public.

Mpshe explained that the law does provide for tapping of phones but it had to be authorised by a judge, and a certificate had to be issued.

"It would be illegal if it was done without being authorised."

With regards to Zuma's representations, Mpshe said he had not made a decision yet.

"I'm still working on the representations but more information keeps coming in and I can't ignore the new information... it may have an impact... on the case... in the future," he said.

Zuma's team submitted new representations earlier in March and a news report last week speculated that the charges may be dropped.

DA leader Helen Zille submitted her own representations on Thursday saying why the charges should not be dropped.

"She has done that on the basis of the law... Now I can't tell her to go and fly a kite... It's quite a process," he explained.

He said all new information had to be verified and therefore time was needed.

"Whatever information I get now, I have to verify... so therefore I can't say when I'm going to make an announcement on a decision... The decision will be made when I'm ready with it".

Mpshe said he was aware of the court timetable on representations at the High Court in Pietermaritzburg, and would ensure his approach did not interfere with those dates.

Mpshe maintained that he was likely to make his decision before August, when Zuma and arms company Thint's trial is due to start.

Zuma case turns on allegedly receiving bribes from Thint to protect them during investigations into arms deal contract awarding processes.