Calling for a shake-up of the international system, Manuel said more prominence had to be given to major developing countries, given the crucial role played by the G20 in tackling the financial and economic slump of the last 12 months.

"The UN has neither the credibility nor the institutional mechanisms to tackle the crisis," Manuel, who served as South Africa's finance minister for 13 years, told a conference at Johannesburg's South African Institute of International Affairs.

"The World Bank and the IMF have roles to play but are not the bodies tasked with fulfilling the coordination function. The G20 has emerged as a major player in global governance," he said.