The Special Investigating Unit has found that President Jacob Zuma was enriched by state-funded improvements to his Nkandla home, but placed the blame for millions lost as the project escalated into "unacceptable extravagance" on his architect Minenhle Makhanya.

It said its investigation showed that, through Makhanya's direct doing, the state suffered losses of some R155 million and many people benefited, including Zuma and his family in the sense that the value of their home was enhanced.

"Clearly, to the extent that these claims are well-founded, the president and his family were enriched," the watchdog unit said in a 245-page report tabled in Parliament on Friday.

In her report released in March, Public Protector Thuli Madonsela found that Zuma had derived undue benefit from the improvements made to his homestead in the KwaZulu-Natal hamlet.

But whereas she recommended that he should repay a portion of the cost, the SIU concluded that the best way of recovering state money lost at Nkandla was to claim it from Makhanya.

"Makhanya inter alia increased the scope and extent of the works by designing and authorising items that were not required for security purposes," the SIU said in the report.

As a result of this, the cost of the project "soared from an initial estimate of some R27-million to some R216-million".

The unit said it faced a choice of claiming the losses suffered by the department of public works from an array of people who were enriched, or to seek to recover the full amount from Makhanya himself.

"We chose the latter option," it said.

Explaining the decision, the SIU said if it instituted individual claims these would be restricted simply to the monetary value of the benefit derived and this would be less that the actual losses incurred by public works.

The SIU filed a civil claim for R155.3-million against Makhanya in the KwaZulu-Natal High Court on August 11, and he has hired high profile lawyers to contest the matter.

The SIU report was released to Zuma a week ago, and he submitted a copy of it to Parliament on Thursday.

Also on Thursday, the president sent a letter to Madonsela stating that he was not obliged to rubber stamp her recommendations.

This was in response to a reminder from Madonsela that he had not responded to her report and followed weeks in the opposition piled pressure on the president to heed her urging to pay for luxuries, including a swimming pool and chicken run, added to Nkandla.

Over the next month, a parliamentary ad hoc committee will consider her report, that of the SIU and an inter-ministerial team as well as Zuma's response to these.

The SIU report recalls events in 2009 which blurred the lines between a standard state project to improve security at Nkandla after Zuma become president, and his private plans for improvements to the home where he intends to retire.

It said that the then acting director general of public works Solomon Malebey agreed that the people who had already been hired by Zuma also be appointed by the department to oversee the public security project.

This led to the appointment of four private firms, including Minenhle Makhanya Architects, and to Makhanya becoming the "principal agent" for the whole project. With Malebey's blessing, they noted, these firms "had complete control over the project".

It said that after the police and defence force formally set out all their requirements for security upgrades at Nkandla, Makhanya expanded the project in ways that were not requested and had nothing to do with safety.

"Some of these items would in any case not qualify as security requirements. In other instances, much more was provided than had been requested, in terms of number and size," the SIU said.

"In yet other cases, reasonable modesty made way for unacceptable extravagance."

The SIU said the manner in which the team was appointed and given "almost unchecked powers" were of grave concern, adding that state departments abdicated their responsibilities.

"The sad result is that a project that could have been undertaken at a cost of some R60.6-million ended up costing about R216-million. By any standard this is a large sum of money.

"The public concern is accordingly understandable."

Despite the money spent, the SIU suggests in the final paragraphs of its report that security measures at Nkandla were still inadequate.

"In our respectful view, a further evaluation of the security situation by the SAPS [South African Police Service] should be undertaken as soon as possible".

The SIU was mandated by Zuma in December to probe what had happened at Nkandla, but later conceded that its staff were not granted access to the property for seven months. Its report firmly denies that there was any political meddling in favour of Zuma.

It said a controversial incident in which the status of its investigation was changed from finalised to "ongoing" at the time Madonsela released her report was not intentional, but the result of miscommunication and inexperience on the part of staff, who were facing disciplinary action.