Public Protector Busisiwe Mkhwebane has denied allegations of interference made by the Public Servants Association (PSA).
According to the Financial Mail, the PSA was set to meet at the Public Protector's office this week to plan its submission to Parliament's inquiry into Mkhwebane's fitness to hold office.
PSA assistant general manager Reuben Maleka, who spoke to the Financial Mail, said there have been complaints, mainly from investigators in her office, concerning interference in their work and illegal surveillance.
Speaking to News24, Public Protector spokesperson Oupa Segalwe said Mkhwebane was mandated to determine how investigations were conducted, and "all investigations are the Public Protector's".
"Only she determines how they should be conducted. This power is drawn from the Public Protector Act in section 7.
"She has delegated her investigation powers to the investigation staff in terms of this section. Therefore, investigators do not work autonomously. Accordingly, the issue of 'interference' does not arise," he said.
The PSA, which consists mostly of Public Protector employees, raised concerns of mismanagement at the Office of the Public Protector and vowed to call on Parliament to remove Mkhwebane, News24 previously reported.
Segalwe said the Public Protector does not tolerate ill-discipline when it came to how she handled human resource issues.
"The Office of the Public Protector must lead by example and as such will not tolerate ill-discipline. It is also the Public Protector's view that, given the nature of their work and the kind of information they get access to during the performance for their duties, all investigators must be vetted."
But the Public Protector has experienced blowback from employees in her office.
The PSA previously accused Mkhwebane of "silencing" the union with threats of dismissals after it raised concerns about the purging of officials.
News24, in partnership with amaBhungane, reported that the head of the Office of the Public Protector in the Free State also submitted an affidavit to Parliament asking it to investigate Mkhwebane's conduct.
In his submission, the staff member made serious allegations of misconduct over her handling of the investigation of the Vrede dairy farm scandal and described a "toxic work environment".
In a statement, Mkhwebane said the trend was "worrying" and could be a result of external parties gunning for her "impeachment".
The PSA told the Financial Mail that most staff members in her office felt Mkhwebane was compromised, saying its members were being victimised.