The decision to suspend two senior correctional services officials was based on "compelling reasons", Minister Nosiviwe Mapisa-Nqakula said on Tuesday.

Briefing the media in Pretoria, Mapisa-Nqakula defended the decision to suspend national commissioner Xoliswa Sibeko and the department's acting chief financial officer Nandi Mareka.

The two were placed on immediate precautionary suspension on Monday following allegations over the renting of accommodation for senior executives with "exorbitant cost" to the taxpayer.

"There must have been compelling reasons. I wouldn't just wake up in the morning and impose a suspension."

She said the Public Service Commission team would investigate Sibeko's conduct and report back within two weeks.

"Obviously I cannot have instability in the department, prolonged instability. It has instilled a lot of anxiety.

"I believe that as the Minister I have very strong reasons to believe that I need an investigation on this matter".

However, Mapisa-Nqakula was adamant that these precautionary suspensions did not imply guilt.

"I am not judging," she said.

It was alleged that Sibeko and her Gauteng counterpart Thozama Mqobi-Balfour were renting properties in Pretoria's Woodhill golf estate at a cost of R30 000 per month.

The rentals - which were not securitised - were being used while official residences remained empty, Mapisa-Nqakula confirmed.

Hierarchically it was the executive responsibility of the Minister to approve the money for the residence of a commissioner and then the commissioner approved rentals from her position down the chain.

However Mapisa-Nqakula, who is new to the department, said the approvals were a "very complex process" and the investigation would deal with how the decisions were made.

"Obviously I will take responsibility for all the decisions that were made by my predecessor [Ngconde Balfour]."

Democratic Alliance shadow minister of correctional services James Selfe had called for Balfour to be questioned over the housing scandal involving his wife.

"The national commissioner Xoliswa Sibeko who lives in the same estate, has been placed on precautionary suspension pending an investigation, and yet she has not."

Reacting to a radio interview with department spokesperson Manelisi Wolela earlier on Tuesday, Selfe said he had implied that the accommodation decision had indeed been approved by Balfour.

"If this is indeed the case, it points to gross conflict of interest, as Mqobi-Balfour is former Correctional Services Minister Ngconde Balfour's wife, as well as wasteful and fruitless expenditure.

"Was Balfour in effect, through his wife, approving his own lavish housing at the taxpayers' expense?"

Selfe said his party would insist that these matters be added to the Public Service Commission's investigation