The State Capture inquiry says former president Jacob Zuma has no right to insist to be furnished with a list of questions as a condition for him to voluntarily take the stand.
In a statement on Thursday‚ the commission said it had been waiting more than six weeks for Zuma to furnish a written undertaking that he would appear before it.
Now‚ it says it will have make other plans.
"The commission hereby confirms that in April 2019 it set aside 15 to 19 July 2019 as the dates for the appearance before it of [Zuma] in order to enable him to give his side of the story in response to the statements or affidavits and evidence of certain identified witnesses‚" the commission said.
"It is contemplated that [Zuma] would come back and appear before the commission later in the year to give evidence on other issues or matters."
It said that it had been in consultation with Zuma's attorneys since the end of April‚ asking that the former president furnish it with a written undertaking that he will appear before the commission on the given dates.