"So far three people have been arrested and two other suspects are expected to hand themselves over to the Hawks", spokesman Hangwani Mulaudzi said in a statement.
ANC Secretary-General Ace Magashule said the party's national executive was split on when Zuma should step down, although the party expected him to respond to the order by Wednesday.
Besides the pressure from the ANC, Zuma is facing a no-confidence motion in parliament set for February 22.
ANC chief whip Jackson Mthembu said Deputy President Cyril Ramaphosa, whose election as head of the ANC in December marked the beginning of the end of Zuma's tenure, could be sworn in as head of state as early as Friday. "They have not been arrested or charged with anything and are still free as we speak‚" he told TimesLIVE.
The South African Federation of Trade Unions welcomes the Hawks' raid on the Gupta compound in Saxonwold, Johannesburg this morning, the arrest of Ajay Gupta, and the simultaneous arrest of Peter Thabethe, former head of the Free State Agriculture Department, in connection with the investigation into the Vrede Dairy Farm scandal.
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She said she would meet the NCA on Thursday following a week of talks with charity bosses, regulators and experts. Oxfam's corporate partners, including Mark & Spencer, Heathrow Airport and Waterstones, are asking questions.
SAFTU also continues to insist that these crimes are not confined to a few businesses, families and politicians - a "Guptocracy" - but is an inherent feature of a monopoly capitalist system, whose ruling class captured the state years ago and still dominates economic policy-making today. A lawyer for the Gupta family said he could not comment on the raid because he had yet to see the search warrant.
Finance Minister Malusi Gigaba said Zuma would speak at 0800 GMT and satellite trucks were in position overnight.
However, Zuma's office denied there had been any "official communication" of an impending address.
Reuters reports that police also raided the offices of the Oakbay holding company on Wednesday, according to a security guard outside the building in the Sandton financial district. "It's very specific items that they are looking for here and elsewhere‚" the source said. Under South African law, suspects can not be named until they appear in court.