Pretoria - President Jacob Zuma needed more information before responding to findings on his Nkandla home, his office said on Thursday after he missed a deadline to report to Parliament on the matter.
"President Jacob Zuma is still seized with preparing the report to the Speaker on the upgrades at his Nkandla home, as undertaken to the Speaker of the National Assembly," Zuma's spokesman Mac Maharaj said in a statement.
"The president will submit his report as soon as possible after receiving all the necessary information required for the preparation of the report."
The Democratic Alliance said the delay was unacceptable, and it would urge Speaker Baleka Mbete to reject it and demand a swift response from the president.
Zuma had undertaken to hand Mbete a comprehensive report on the outcome of three separate investigations into state spending of some R246 million on his private home in the KwaZulu-Natal hamlet by the end of Wednesday.
Pressed for further details on the delay, Maharaj said: "It would appear one of the issues is the final report of the Special Investigating Unit."
The SIU recently confirmed that its final report had been delayed.
Last week, the head of the unit, Vas Soni, told MPs this was partly because two people implicated had failed to respond to questions, partly because investigators were only given access to Nkandla on July 3, more than six months after the start of the probe. He declined to name the two people.
Maharaj said he believed the SIU's report was due soon, and that Parliament had been informed of the president's decision to defer his response.
Public spending on security upgrades at Nkandla have turned into one of the major controversies of the Zuma presidency as costs escalated and it emerged that the project included a swimming pool, an amphitheatre, and chicken run.
In March, Public Protector Thuli Madonsela found Zuma had derived undue benefit and should pay for some of it out of his own pocket.
Zuma declined to respond to Madonsela's report in full within the required fortnight and said instead he would wait for the SIU's findings.
On July 5, the African National Congress Chief Whip's office said Zuma had received the provisional SIU report and would provide Mbete with a final and comprehensive response within 30 days.
The head of the DA's federal executive, James Selfe, said it was untenable that more than three months after Madonsela published her report, Parliament still had no full explanation from the president.
Mbete must "make it clear to the president that his submission is overdue and must come to Parliament immediately", he added.
"Should she fail to do so, she will be complicit in a cover-up to shield the president from accountability, and will undermine the integrity of this fifth Parliament.
"It is time for Parliament to flex its muscles and to make it clear that it will not be messed around for a day longer."
The DA has petitioned Mbete in vain to reconstitute an ad hoc committee to consider the various Nkandla findings, after one set up by her predecessor Max Sisulu concluded it had too little time to do so properly before the May elections.
It is unclear when the SIU will conclude its probe. It was launched after Zuma signed a proclamation on December 18 giving the unit the go-ahead to investigate "intentional or negligent loss of public money" at Nkandla.
Soni told Parliament's justice portfolio committee last week it pained him the SIU report was being held up as it reflected poorly on him and his staff. He could not say when it would be complete.