JOHANNESBURG, July 11 (Reuters) - Shops were looted overnight, a section of highway was closed and stick-wielding protesters marched through Johannesburg on Sunday, as sporadic violence following the jailing of former South African President Jacob Zuma spread. The unrest had mainly been concentrated in Zuma"s home province of KwaZulu-Natal (KZN), where he started serving a 15-month sentence for contempt of court on Wednesday night. read more President Cyril Ramaphosa said on Sunday there was no justification for violence and that it was damaging efforts to rebuild the economy amid the COVID-19 pandemic. Zuma"s sentencing and imprisonment have been seen as a test of the post-apartheid nation"s ability to enforce the law fairly - even against powerful politicians - 27 years after the African National Congress (ANC) ousted white minority rulers to usher in democracy. read more But his incarceration has angered Zuma"s supporters and exposed rifts within the ANC. Police said criminals were taking advantage of the anger to steal and cause damage. National intelligence body NatJOINTS warned that those inciting violence could face criminal charges. NatJOINTS said in a statement that 62 people had been arrested in KZN and Gauteng, the country"s main economic hub where Johannesburg is located, since the violence began. OPPORTUNISTIC CRIMINALS Supporters of former South African President Jacob Zuma block the freeway with burning tyres during a protest in Peacevale, South Africa, July 9, 2021. REUTERS/Rogan Ward/File Photo A police officer detains a suspect during a protest, as violence following the jailing of former South African President Jacob Zuma spread to the country"s main economic hub in Johannesburg, South Africa, July 11, 2021. REUTERS/Sumaya Hisham The remains of a burnt car and a sign block the road after stick-wielding protesters marched through the streets, as violence following the jailing of former South African President Jacob Zuma spread to the country"s main economic hub in Johannesburg, South Africa, July 11, 2021. REUTERS/Siphiwe Sibeko 1/7 A police officer detains a suspect during a protest, as violence following the jailing of former South African President Jacob Zuma spread to the country"s main economic hub in Johannesburg, South Africa, July 11, 2021. REUTERS/Sumaya Hisham The Johannesburg Metropolitan Police Department (JMPD) said there had been looting in the Alexandra township and Jeppestown suburb on Saturday night. The main M2 highway was closed off after there were reports of shots being fired at passing vehicles. A Reuters TV crew saw a column of protesters brandishing sticks, golf clubs and branches as they whistled and marched through Johannesburg"s Central Business District, where liquor stores had been burgled and shop windows smashed. The sale of alcohol is currently banned under lockdown restrictions designed to ease pressure on hospitals during a severe "third wave" of COVID-19 infections. KZN police spokesman Jay Naicker said there had also been more looting in eThekwini, the municipality that includes the coastal city of Durban. "We saw a lot of criminals or opportunistic individuals trying to enrich themselves during this period," he said. Zuma was given the jail term for defying an order from the constitutional court to give evidence at an inquiry that is investigating high-level corruption during his nine years in power until 2018. He denies there was widespread corruption under his leadership but has refused to cooperate with the inquiry, which was set up in his final weeks in office. Zuma has challenged his sentence in the constitutional court, partly on the grounds of his alleged frail health and the risk of catching COVID-19. That challenge will be heard on Monday. read more Parliament"s presiding officers said on Sunday that they were "sympathetic to the personal difficulties confronting former President Jacob Zuma. However, the rule of law and supremacy of the constitution must prevail".