F.W. de Klerk said that he was "deeply disappointed" in the scandal-dogged leader.
Zuma turned 75 on Wednesday.
The president fired his popular finance minister to widespread criticism.
Several of Zuma's ministers are backing calls for him to resign as ANC leader.
Zuma may face the reinstatement of 783 corruption charges, but he's still popular with rural South Africans.
Former South African President Thabo Mbeki says that $50 billion leaves Africa illicitly each year.
Zuma is unlikely to step down but the judiciary's authority in South Africa has been reaffirmed.
The policies of South Africa's former president resulted in hundreds of thousands of premature AIDS deaths.