South Africa's prison service has said it will challenge a court decision that sent former president Jacob Zuma back to jail.

"Having carefully studied the judgement, Correctional Services is convinced that another court may arrive at a different conclusion," the Department of Correctional Services (DCS) said in a statement.

The Supreme Court of Appeal had on Monday ordered Mr Zuma to return to prison after upholding an earlier ruling that his medical parole had been unlawful.

The 80-year-old was given a 15-month sentence last year for contempt of court over his refusal to testify during an investigation into corruption.

But he was released after two months in jail, after his lawyers argued that he had an undisclosed terminal illness and needed medical care that could not be provided in prison.