Clinton also said that the U.S. was concerned that China's quick economic push into Africa risks disturbing efforts to help the region develop a more mature and transparent economy.

But Chinese Ambassador to Zambia Zhou Yuxiao last week in an interview with the local Post newspaper said, "We believe our investment in Africa is not big yet because China's capacity is limited and we look at African countries who want relations with China as friends and we are willing to develop good relations."

(Additional reporting by Michael Kan in Beijing.)