High Court Judge Elias Matojane ruled last Wednesday that the September decision to place the 79-year-old on medical parole was "unlawful".

The same judge on Tuesday decided to allow an appeal.

"In my view, this matter merits the Supreme Court of Appeal's attention," he said at the end of a virtual hearing.

He said another court may find that Zuma should be treated with "compassion, empathy and humanity" because of his ill health and advanced age.

The former president was handed a 15-month jail sentence in July for contempt of court after he refused to give testimony to corruption investigators.

His jailing sparked violent protests and looting in his home province of KwaZulu-Natal that spread to South Africa's financial hub Johannesburg in July, claiming more than 350 lives.

It was the deadliest violence in South Africa since the end of white-minority rule in 1994.

The former president was granted medical parole on September 5, but the exact reasons were never revealed. He has since returned to his $17 million estate in rural Nkandla.

While he was in prison, he was taken to hospital for surgery to treat an undisclosed ailment.