The National Prosecuting Authority was concerned that its head, Mokotedi Mpshe, is regarded as a suspect in a police investigation into some of the NPA's senior management.

NPA spokesman Tlali Tlali said the authority learned from papers filed in a labour dispute that some of its senior management, including Mpshe, were regarded as suspects in the investigation by Gauteng police Commissioner Richard Mdluli.

"There has been a considerable communication and meetings between Advocate Mpshe and Commissioner Mdluli in this regard, and no indication has been given to him that he is a suspect.

"The acting head of the National Prosecutions Service, Advocate Sibongile Mzinyathi, has co-operated with the SAPS.

"He has also not been informed that he is a suspect, nor was he warned as a suspect as required by law when he was interviewed about the matter," Tlali said.

Another concern, Tlali added, was that an intercepted telephone conversation of former Scorpions head Leonard McCarthy "appeared to be the basis of this investigation".

The NPA raised questions about the legality of making a legal interception public as the SAPS had done in the labour dispute.

"It has also not been made clear to those interviewed whether this interception was made in terms of the law," Tlali said in a statement.

"While the NPA is willing to co-operate in any investigation, it is very concerned about whether this matter is being handled in good faith, and will seek to raise its concerns as soon as possible with the Minister of Safety and Security, Mr Nathi Mthethwa, and the acting National Police Commissioner Tim Williams."

Tlali could not immediately be reached for further comment.

Gauteng police spokesman Director Govindsamy Mariemuthoo was unable to comment on the matter.

"I can't comment because I don't know about it," he said.