The South African Security Agency (SSA) is considering using investigative journalist and author Jacques Pauw as a witness, attorney Willem de Klerk told News24 on Thursday.
While rumours have been flying thick and fast that Pauw, author of The President's Keepers, was likely to be arrested at his book launch, De Klerk was unable to confirm the news.
"We are in contact with authorities to ensure that there is clear communication between us," he said.
However, he added that they have been informed that the SSA wanted to "potentially use Pauw as a witness".
He did not want to elaborate on his comments.
In the interim, Pauw and his lawyers are expected to meet to prepare a bail application in the event that he is arrested.
Hawks spokesperson Brigadier Hangwani Mulaudzi told News24 that they have turned their attention to whistleblowers, who leaked the sensitive and confidential information contained in the book.
Not bowing down
Since his book's release on October 29, Pauw and NB Publishers have been sent two cease and desist letters from the SSA.
The book reveals how the agency was allegedly used to protect President Jacob Zuma from legal persecution.
The South African Revenue Service (SARS) also said it was considering legal steps against Pauw and the Sunday Times, who published an extract of the book.
The extract alleged that Zuma received monthly payments of R1m from Roy Moodley in 2009 when he was already president, without declaring it to SARS.
However, NB Publishers said it would "proudly" defend Pauw from any possible legal action. In a statement, the book publishers said it was "grateful and heartened" for the support received from civil society groups and the South African public.
"We have refused to bow to the pressure and will continue to do so," the statement read.
NB Publishers said, since the book's release on October 29, 25 000 copies have been sold in South Africa, with an additional 50 000 ordered.
"The President's Keepers is the fastest-selling book in South Africa since official Nielsen data began in 2004, and it was also a global bestseller on Amazon at the weekend."
*NB publishers are a subsidiary of Media24 which owns News24.