US Secretary of State Hillary Rodham Clinton on Friday called on South Africa to take a leading role in driving slumping economies across the world's poorest continent during the worldwide financial crisis. In a speech to South African business leaders here, Clinton said that despite setbacks the country is “uniquely positioned” to propel economic growth throughout Africa if it sticks to sound financial principles, embraces open trade and promotes foreign investment. “The economic success of Africa hinges ... to a great extent on the economic success of South Africa,” she said. “This is both a responsibility and an opportunity.” South Africa, Clinton said, “is uniquely positioned to advance its own economic trajectory and to propel economic growth on the African continent as a whole.” South Africa cannot “exist as an island of relative prosperity amid a sea of untapped opportunity elsewhere on the continent,” Clinton said on the second leg of a seven-nation tour of Africa aimed it part at bolstering trade.