Tiyiselani Mashele (left), co-founder of Biking Bandits, cycles during the Homies Night Ride in Soweto, South Africa on Thursday. Photo: AFP

President Cyril Ramaphosa on Monday said the deadly unrest gripping the country is unprecedented in post-apartheid South Africa as he deployed troops to help police crush the violence and looting sparked by the jailing of ex-president Jacob Zuma.

Soldiers were sent onto the streets of the country's two most densely populated provinces of Gauteng, which houses the country's economic hub Johannesburg and KwaZulu-Natal, Zuma's home province.

"Over the past few days and nights, there have been acts of public violence of a kind rarely seen in the history of our democracy," said Ramaphosa in a televised address to the nations, adding he was speaking with "a heavy heart."

Overwhelmed police are facing mobs who have ransacked stores, carting away anything from crates of alcohol to beds, refrigerators and bath tubs. 

Ten people have died, some with gunshot wounds sustained before the army was deployed, and 489 people have been arrested.

Ramaphosa said he had "authorised the deployment of defence force personnel in support of the operations" of the police.

Earlier the army said they will assist police "to quell the unrest that has gripped both provinces in the last few days."

It was the second successive day Ramaphosa addressed the nation on the violence.

The violence raged as the Constitutional Court heard an application to review its landmark decision to jail Zuma for contempt of court. Judgement was reserved after a marathon 10-hour sitting. 

The country's top court on June 29 slapped Zuma with a 15-month term for snubbing a probe into the corruption that stained his nine years in power.

Zuma began the sentence Thursday but is seeking to have the ruling set aside.

"This court made fundamentally rescindable errors," Zuma's lawyer Dali Mpofu argued in an on-line hearing. 

But one of the judges, Steven Majiedt, bluntly said Zuma had been convicted "because he disobeyed the order of this court." Mpofu responded that Zuma was being "punished for more than the disobedience" of a court order.

Despite his reputation for graft and scandal, the 79-year-old former anti-apartheid fighter remains popular among many poor South Africans.

The epicenter of the unrest is Zuma's home region, the southeastern province of KwaZulu-Natal. In its capital Pietermaritzburg smoke billowed from the roof of a large shopping mall. Banks, shops and fuel stations in the city were shut. Retail shops in Durban and Johannesburg were ransacked Monday while police watched. 

A mall in Johannesburg's upmarket Rosebank suburb closed early following "a tipoff that the looters are on their way," a security guard told AFP.