Prosecutions head Mxolisi Nxasana should be commended for taking a stand against his deputy Nomgcobo Jiba and national police commissioner Riah Phiyega, the Democratic Alliance (DA) said on Friday.

"Mxolisi Nxasana has conducted himself with distinction throughout this debacle," DA MP and former National Prosecuting Authority prosecutor Glynnis Breytenbach said in a statement.

She praised Nxasana, who is National Director of Public Prosecutions, for making it clear that Jiba enjoyed protection from a source much higher than Phiyega.

Nxasana told reporters in Pretoria on Friday that Phiyega's intervention in the case against Jiba was worrying.

"Because of my position, I wouldn't venture into saying what she is doing is defeating the ends of justice. All I am saying is that I am concerned with her involvement in the matter. I asked her, and I am asking you, does she really do this in all other matters where ordinary suspects are involved?"

Nxasana said he got a call from Phiyega after senior police officers delivered a summons against Jiba. Since Jiba was not at her workplace, Nxasana was handed the summons, which he delivered to Jiba.

He said Jiba refused to accept the summons. It required her to appear on criminal charges in the Pretoria Magistrate's Court on April 21.

"When I received a call from the national police commissioner, to be honest I still don't know what was the reason for her call. She said the summons was not issued properly," Nxasana said.

"I'm still battling to understand what it is that she wanted from me. I am talking with confidence as jurist and as a person who received the summons."

On Wednesday, Phiyega's spokesperson Lt-Gen Solomon Makgale denied they were looking for Jiba, and said no summons had been issued.

"It is worth mentioning that the issuing of the summons was not done in consultation with the [South African Police Service's] investigating officer," he said at the time.

The charges against Jiba relate to her failed bid to lay murder and racketeering charges against suspended KwaZulu-Natal Hawks head Maj-Gen Johan Booysen.

In February last year, Durban High Court Judge Trevor Gorven set aside the charges, saying they did not meet even minimum standards.

Breytenbach said Nxasana had done everything "by the book".

"The fact that Jiba produced a 'sick note' 36 hours after the fact is telling, and her refusal to accept the actual summons document is an indictment on her as a senior prosecutor," Breytenbach said.

"She has brought not only the NPA into disrepute, but also the profession of prosecuting and is an embarrassment to all other prosecutors."

Breytenbach called on President Jacob Zuma to take action against Jiba.

The South African Policing Union said it was shocked by Phiyega's actions.

"This is not just political interference, this is a pure criminal offence," general secretary Oscar Skommere said in a statement.

"The national commissioner should be charged criminally for defeating the ends of justice. This latest revelation makes it a necessity that General Phiyega step aside pending an inquiry into her fitness to hold office."

The union called on Zuma to suspend her.