South Africa's top court ruled on Friday that former president Jacob Zuma had failed in his bid to have his 15-month jail sentence for failing to attend a corruption inquiry overturned.

The sentence was handed down after Zuma failed to testify at an inquiry probing corruption during his 9-year rule, one seen as a test of post-apartheid South Africa's ability to enforce the rule of law, particularly against powerful politicians.

Zuma, recuperating in hospital after undergoing surgery for an undisclosed illness, asked the court in July to revoke its sentence for contempt arguing it was excessive, and that jail would endanger his health and life.

In a majority decision, the Constitutional Court rejected his arguments.

It was the latest legal setback for the 79-year-old anti-apartheid veteran from the ruling African National Congress (ANC), whose presidency between 2009-2018 was marred by widespread allegations of graft and malfeasance. He denies wrongdoing.

His jailing on July 7, after handing himself over to police at the last minute, triggered some of the worst riots and looting in decades, with more than 300 people killed and thousands of businesses pillaged and razed.

The violence, which President Cyril Ramaphosa described as a "failed insurrection", was also fuelled by simmering frustration among largely Black communities still living in squalid conditions long after the ANC swept to power in South Africa's first democratic elections in 1994.