The Inspector General of Intelligence is probing how Jacob Zuma's lawyers managed to lay their hands on the tape recordings which allegedly implicated former NPA head Bulelani Ngquka and former Scorpions boss Leonard McCarthy.

The tapes, which implicated the two men in a conspiracy against the ANC leader, were crucial in the National Prosecuting Authority's decision to drop charges against Zuma.

Zuma's lawyer Michael Hulley has refused to say how he got the tapes.

Spokesman for the office of the Inspector General, Imtiaz Fazel, said: "Certainly we are looking into the source and nature of those communications and whether they were unlawfully obtained.

"This matter has been subject to scrutiny for quite some time now but with regards to the matter under discussion I would say since the matter broke in the media we started to look into it," Fazel said.