New data from Corrections, reveals more than 3,000 gang members and associates make up the just over 10,000 sentenced and remand prisoners.
It equates to about a third of the country's estimated gang population.
Corrections Association President Floyd du Plessis says the chances of rehabilitation for these inmates is low.
He says it needs to be possible for prisons to separate people, based on their intentions to turn their lives around.
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