Former South Africa Social Security Agency (Sassa) CEO Thokozani Magwaza has described Social Development Minister Bathabile Dlamini as drunk with power.

During his testimony on Friday at the Office of the Chief Justice in Midrand, Magwaza described how Dlamini barged into an exco meeting without warning and reprimanded him in front of his subordinates.

He added that Dlamini would also change advisors on a whim.

"[The] problem was, [the] minister was running Sassa like her own shop," he said.

Magwaza said that during a Sassa exco meeting in February, Dlamini made a surprise appearance, attending the meeting for the first time without notifying Magwaza.

Dissatisfied with suggestions made by executives, she lashed out at Magwaza, telling him to "concentrate on day-to-day business" and let the workstreams do their work as they "reported to her".

"She walked outside. I followed her and I said: 'But minister, this is unfair. You are vilifying me in front of my staff.' She said nothing. Her security then stood around her to protect her as if I was trying to attack her."

Magwaza added that Dlamini had been warned on several occasions that the workstreams would be seen as working parallel to the Sassa exco.

"I said: 'Mama, we are trying to push against a parallel process. This is a parallel process'."

During cross-examination on Monday, Dlamini however said she was not aware that Magwaza and former Sassa director general Zane Dangor viewed workstreams as a parallel process.

Magwaza took the stand on the fifth day of the inquiry.

Dlamini had faced four days of cross-examination where she was reprimanded by the chair of the inquiry, retired judge Bernard Ngoepe, for avoiding questions.

The Constitutional Court ordered last year that an inquiry be held to investigate whether she should be held personally liable for the costs incurred during the Sassa payments crisis.

Dlamini said it was "untrue" that the workstreams she established and which reported to her were meant to operate parallel to the work of Sassa, or undermine the agency's work.

The inquiry was established to investigate whether Dlamini sought the appointment of individuals to lead the various "workstreams" to report directly to her.

Further, the Constitutional Court ordered the inquiry to investigate the details of the appointments, such as when people were appointed, who they reported to, and the dates and contents of the report of the workstreams to the minister.

Lastly, the inquiry will also look into why the minister did not disclose this information to the court.

During cross-examination, Geoff Budlender, the advocate for Black Sash, which took Sassa to the Constitutional Court last year, argued that Dlamini's most important duty was to ensure that 17-million people depending on social grants received them on time.

Last year, Magwaza said in an affidavit that the workstreams were given a broad mandate to take over the implementation of the project, and that the social security agency was instructed not to interrupt or delay them in their work.