A preservation order is expected to be served on Trillian and McKinsey on Tuesday for assets worth around R1.6bn, the National Prosecuting Authority has confirmed.
Both companies are linked to the Gupta family.
NPA spokesperson Luvuyo Mfaku said the order relates to consultancy work done by the companies for Eskom and Transnet.
The preservation order was obtained on December 14 last year, and once it is served, a curator will ensure that the companies' accounts are frozen and the assets are preserved.
"They have 90 days to indicate whether they are defending the matter. If they do, the onus is on them to satisfy the court that they acquired [the assets] through lawful means," he explained.
"If they prove that they acquired it legally, it will be unfrozen and go back to them. If they fail to prove they are the lawful owners, after 90 days the NPA will apply for a forfeiture order."
He said contrary to reports, the Guptas are not the planned recipients of a summons.
The City Press reported on Monday afternoon that the Asset Forfeiture Unit was set to serve a summons on them and their associates directly.
On Monday evening, the publication reported that the Hawks had obtained an arrest warrant for at least one Gupta brother and a number of the family's associates, and were waiting for prosecutors at the NPA to sign warrants off.