Fast bowler Ntini will replace Zimbabwean Heath Streak, who returns home in August for the New Zealand and India series.

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"In principle the deal has been approved, and we're sorting out the conditions we will release him on," UCB chief executive Gerald Majola told Reuters on Wednesday.

"He's a rhythm bowler, and the feeling is that he needs to be bowling before our season starts."

Majola said final approval for Ntini's release could be completed by the end of the week.

South Africa, whose season ended against West Indies last month, resume with a home series against New Zealand in October.