The long-running corruption trial of South Africa's jailed ex-president Jacob Zuma is due to resume virtually today, despite deadly violence that swept the nation after his imprisonment in an unrelated case.

Mr Zuma faces 16 charges of fraud, graft and racketeering related to the 1999 purchase of fighter jets, patrol boats and military gear from five European arms firms when he was deputy president.

He is accused of taking bribes from one of the firms, French defence giant Thales, which has been charged with corruption and money laundering.

The trial started in May after numerous postponements and delays, as Mr Zuma's legal team worked fervently to have the charges dropped.

The 79-year-old, who appeared in person for the opening, proclaimed his innocence.

Thales has also pleaded not guilty, and the next hearing was set for today.

On 29 June, Mr Zuma was separately found guilty of contempt of South Africa's top court for snubbing graft investigators probing his time as president. He was jailed a week later.

South Africa was then plunged into chaos, with looting and rioting erupting in Mr Zuma's home region KwaZulu-Natal as well as Gauteng province, claiming more than 200 lives.

The unrest was widely seen as at least partially in response to Mr Zuma's imprisonment.

Today's hearing, which will be held virtually, could reignite tensions that had eased by the weekend, analysts warn.

"People will be watching the behaviour of judges," said Sipho Seepe, a fellow of the University of Zululand in KwaZulu-Natal.

"If they feel justice is not done, they will protest."

Today's hearing will focus on an application by Mr Zuma's legal team for chief prosecutor Billy Downer to recuse himself from the case over claims he leaked information to the media.

The National Prosecuting Authority said it would "vigorously" oppose the application.

Despite the digital staging of the hearing, supporters of Mr Zuma are likely to gather in front of the Pietermaritzburg High Court as they have for past hearings.

His lawyers claim the virtual format is unconstitutional and have applied for the trial to be adjourned.

His foundation confirmed on Twitter late yesterday that the ex-president would attend the hearing virtually "for the postponement application of his trial".

Mr Zuma and his backers have repeatedly dismissed scrutiny of the ex-president's conduct as politically motivated and warned his jailing would spark unrest.

But they deny being behind the recent turmoil.

Mr Zuma, once dubbed the "Teflon president", is meanwhile seeking to overturn his 15-month jail sentence.

He was arrested for disobeying a Constitutional Court order to testify before a judicial panel probing corruption during his presidency.