The department of correctional services will not discuss whether rightwinger Clive Derby-Lewis had been refused parole, it said on Friday.
Earlier, Derby-Lewis's lawyer Marius Coertze confirmed a radio news report that his client's parole had been refused.
"Yes indeed," he said, when asked to confirm the report on SAFM.
However, ministerial spokesman Sonwabo Mbananga said it was actually Janus Walusz, Derby-Lewis's co-accused in the murder of SA Communist Party leader Chris Hani, who had been refused parole.
Derby-Lewis and Polish immigrant Walusz are serving life sentences for the murder of Hani in 1993, the year before South Africa's first democratic elections.
Mbananga said: "The application for parole of Janus Walusz has been declined on the basis that the families have not been involved with the process."
That process had to take place first, he said.
Correctional Services Minister Nosiviwe Mapisa-Nqakula had informed the people acting Walusz's behalf and after responding to their request for a reason, she decided to share this information with the nation.
Mbananga said the department would not be communicating on Derby-Lewis's parole application.
Derby-Lewis's legal team said earlier this year that he was being treated for prostate cancer and skin cancer.
His supporters have compared his parole application to that of President Jacob Zuma's former financial adviser Schabir Shaik, who was released on parole following a corruption conviction on the grounds that he had a terminal illness.
Derby-Lewis was convicted of conspiracy to murder and was initially sentenced to death for his role in Hani's assassination, but this was changed to life imprisonment when the death penalty was outlawed in 1995.
He confessed to his role in the assassination to the Truth and Reconciliation Commission, but was not granted amnesty. - Sapa