None of the companies involved in the upgrades to President Jacob Zuma’s Nkandla homestead have been blacklisted, the public works ministry has said.

Replying to a parliamentary question from Democratic Alliance (DA) MP Annelie Lotriet, published on Monday, Public Works Minister Nathi Nhleko said no supplier had been placed on the restricted supplier database.

However, the department would place on the database those suppliers guilty of breaching supply chain management policies and/or Treasury regulations.

The department had continued working with eight out of the 14 companies. They had been contracted between August 2014 to date, he said.

They are Otis, Pro-Hydraulics, Mustapha Cachalia Engineering, Ilangalethu Consult, RG Consulting, Bonelena Construction Enterprise and Projects, E Magubane, and CA du Toit.

DA leader Mmusi Maimane said the revelations were shocking considering the Constitutional Court had found the upgrades were "fraught with corruption and unlawful enrichment".

"It once again proves that the more connected and corruptible you are, the more valuable to the ANC [African National Congress] government you become, and the more illegitimate money you can make."

The party would refer the matter to the Treasury’s chief procurement officer to investigate.

"We are adamant that any company or individual who unduly benefitted from carrying out work at Nkandla must be blacklisted and held accountable for their actions."