Pretoria - Former Vlakplaas commander Eugene de Kock was granted parole on Friday, while Chris Hani killer Clive Derby-Lewis was denied medical parole, Justice Minister Michael Masutha announced.
A decision on Ferdinand Barnard's bail application was delayed.
"In the interest of... nation building, I have placed Mr De Kock on parole," said Masutha.
The time and date of his release will not be made public.
The medical parole board had recommended Derby-Lewis be released. He has terminal lung cancer. But Masutha raised questions about his medical tests.
"There is nothing to suggest that Mr Derby-Lewis's condition is such that he is rendered physically incapacitated... so as to severely limit daily activity," Masutha said.
De Kock is serving two life sentences, plus 212 years for other crimes, Sapa reported. He was denied parole in July last year, despite being eligible after spending 20 years behind bars.
Derby-Lewis was arrested for aiding and abetting Janusz Walus, a Polish immigrant, in the assassination of Hani, and having lent him the gun used to shoot the former SACP leader in the driveway of his home.
Former apartheid-era CCB agent Barnard, was found guilty 17 years ago of the murder of anti-apartheid activist David Webster.
Almost a decade later, Barnard was convicted of the killing. He was also found guilty of the attempted murder of another activist, Dullah Omar, who went on to serve in both former presidents Nelson Mandela and Thabo Mbeki's Cabinets.