Ex-president Jacob Zuma on Friday asked South Africa's top court to rescind its decision to sentence him to 15 months in jail for failing to appear before a graft inquiry.

In papers filed on Friday, two days before the expiry of a deadline for him to surrender to police in preparation for imprisonment, Zuma pleaded that the order be "reconsidered and rescinded."

In an unprecedented ruling, the Constitutional Court on Tuesday handed Zuma a 15-month jail term for snubbing an order to appear before graft investigators.

The 79-year-old was given until Sunday to turn himself in, failing which police will arrest him within three days and take him to jail to start the sentence.

Zuma, in the documents filed on Friday, said he had been advised "it will not be futile to make one last attempt to invite the Constitutional Court to relook its decision and to merely reassess whether it has acted within the Constitution or, erroneously, beyond the powers vested in the court by the Constitution."

He cited his "own unstable state of health… it is my physical life that the incarceration order threatens."

He said it was "no exaggeration to label (the ruling) as cruel and degrading punishment."

In this light, Zuma argued, he believed he was entitled to a court that would examine his request "with dispassionate interest but a keen sense of judicial duty and independence."

The historic verdict has triggered a show of support from the Zuma's fervent but dwindling followers, some of whom made their way to his rural home in the eastern town of Nklandla to express their solidarity.