The authenticity of a letter purportedly sent to President Jacob Zuma by the department of public works in 2010 was questioned on Tuesday.
Public Works Minister Thulas Nxesi's legal adviser Phillip Masilo said the department could not comment on the letter and its contents.
"Public Works Minister Thulas Nxesi is on record that he has not seen this correspondence nor is it in possession of DPW (department of public works)," he said.
"Perhaps the people in possession of the letter can shed light on it."
A copy of a letter titled "Nkandla: security installations at the private residence of his excellency President Jacob Zuma" was electronically circulated to the media by Democratic Alliance Parliamentary leader Lindiwe Mazibuko.
The letter appears to have been signed by the then Public Works Minister Gwen Mahlangu-Nkabinde, her deputy Hendrietta Bogopane-Zulu, director-general Siviwe Dongwana, chief operating officer Ashraf Adam and deputy director-general Rachard Samuels on November 5, 2010.
It was addressed to Zuma.
"Having assumed duty as the minister of public works on the 1 November 2010, I have taken the view that it is prudent to update you on the progress of the above prestige project," the letter reads.
"The fast-track nature of the project necessitates the daily updating of the project plan and for alternate planning methodologies to be employed in order to meet the target date of 30 November 2010."
The upgrades, to be completed by that date, are listed in the letter.
They include: a cattle culvert, perimeter fence, inner high security fence, guard house, tuck shop, refuse and electrical rooms, electrical supply, sewer treatment plant, relocation of families, upgrade of water supply, helipad, excavation for clinic, entrance by-pass, services to park-homes, entrance road, tunnel, safe haven, bullet proof glazing and high impact glazing.
On Sunday, Nxesi said the government spent R206-million on security upgrades and consultants for Nkandla. Included in this amount was R135-million for the "operational needs" of various government departments, R71-million for consultants, and security features such as bullet-proof windows, security fencing, evacuation mechanisms, and fire-fighting equipment. Also included in the total was R26 million to make changes to the project (variation orders).
However he said no houses were built using public money.
Nxesi, Justice Minister Jeff Radebe, Police Minister Nathi Mthethwa and State Security Minister Siyabonga Cwele were part of a task team investigating the costs of the upgrades to Zuma's residential complex after it caused an outcry last year.
Nxesi said Zuma's home, like those of former presidents and former deputy presidents, had been declared a national key point. Cwele said neither Zuma nor his family had any input on the security upgrade.