A South African court is due to decide if a corruption case can proceed against ruling party leader Jacob Zuma. The African National Congress (ANC) head is facing 16 charges relating to a multi-billion dollar arms deal. Mr Zuma, favourite to become president in next year's elections, says the charges are politically motivated and wants them to be dismissed. Hundreds of people are outside the court in Pietermaritzburg to support Mr Zuma after an all-night vigil. Police have closed roads and put up cordons to prevent a fresh outbreak of violence, following clashes in the city of Durban earlier this week. Some of Mr Zuma's supporters have threatened unrest, and some have said they are prepared to kill for the ANC leader. 'Not alone' The hearing is being relayed to the crowd outside on a large screen. The BBC's Mpho Lakaje in Pietermartizburg said the crowd who braved the very cold wintery and drizzly night outside the court was singing and chanting in Zulu "vuli ndlela", which loosely translated, means open the door. Their message was that the Supreme Court should leave the way open for Mr Zuma to become president next year by dropping the case, our reporter says. "We are here to show him he is not alone today," one supporter told the BBC. "Often these judges are political judges and I feel so sad in my heart with Jacob because I love him and I need him to be the president next year," he said. Mr Zuma, aged 66, is due to attend the hearing in Pietermaritzburg later on Friday. If he loses this appeal, his lawyers say they will seek a permanent stay of prosecution. The charges relate to the arms deal in 1999, when the South African government announced its largest post-apartheid arms deal, signing contracts totalling 30bn rand ($5bn; £2.5bn) to modernise its national defence force. The deal involved companies from Germany, Italy, Sweden, Britain, France and South Africa. Mr Zuma has said he will stand down as ANC leader only if he is found guilty of the charges - corruption, fraud, racketeering and money-laundering.