Johannesburg - South Africa has called a news conference for Friday to announce an African candidate for the World Bank presidency, widely expected to be Nigerian Finance Minister Ngozi Okonjo-Iweala, sources familiar with the discussions said on Thursday. South Africa chairs one of the three African seats on the 25-member World Bank board, and Okonjo-Iweala’s candidacy was being proposed after consultations between President Jacob Zuma and Nigerian President Goodluck Jonathan, the sources said. A statement from the Treasury said the Finance Ministers of Angola, Nigeria and South Africa would hold a news conference in Pretoria on Friday, although it did not disclose details of the agenda. Okonjo-Iweala and former Colombian Finance Minister Jose Antonio Ocampo are set to make the first concerted challenge to the US grip on the top job at the World Bank, sources told Reuters this week. Brazil said this week that both Okonjo-Iweala and Ocampo would be “great” candidates to replace Robert Zoellick as head of the Washington-based development institution, the latest sign of emerging nations wanting more say in how it is run. Washington has held the presidency since the bank’s founding after World War Two, while a European has always led its sister organisation, the International Monetary Fund. Despite the push by emerging nations, the United States has the bank’s largest voting share and is expected to win the support of most developed nations, making it likely that another American will succeed Zoellick. The United States has yet to identify a nominee.