Former Public Protector Thuli Madonsela warned against destroying the chapter 9 institution as it comes under fire for decisions her successor, Busisiwe Mkhwebane, has made.

"I think that my successor should not be critiqued by me," said Madonsela said on Wednesday on the sidelines of a conference of mediators that was held on the outskirts of Paarl, in the Western Cape.

She said people were entitled to criticise the Public Protector, but should be mindful of the potential consequences.

"All I can say is we should be careful that we do not put the institution under siege," she said, adding that it "could allow politicians to control the institution".

Madonsela said she was happy that there was more information on the commission of inquiry into state capture, after inquiry chair Deputy Chief Justice Raymond Zondo released further details about it on Wednesday.

She urged anybody with information that might help the inquiry to send it to Zondo. If they had safety fears over whistleblowing, they should tell Zondo this.

Asked about Mkhwebane's handling of the Estina Dairy report, she said she did not want to besmirch her successor's work.

However, she said that while she was in office, the Estina matter was sent back twice by her for further investigation.

The first investigation had not mentioned who the "players" were, and the second was that there were allegations of corruption.

The office's investigating manual required it to investigate "relationships" in matters alleging corruption. "And that meant we had to start again," said Madonsela.