DAR ES SALAAM, Tanzania — U.S. Secretary of State Hillary Rodham Clinton on Saturday warned of a creeping "new colonialism" in Africa from foreign investors and governments interested only in extracting natural resources to enrich themselves.

African leaders must ensure that foreign projects are sustainable and benefit all their citizens, not only elites, she said.

Clinton did not identify any perceived culprits, but a day earlier she had urged scrutiny of China's large investments and business interests in Africa so that the African people are not taken advantage of. She said U.S. diplomats in Africa had been asked to provide Washington with assessments of Chinese projects in the countries to which they are assigned.

"We saw that during colonial times, it is easy to come in, take out natural resources, pay off leaders and leave," Clinton said Saturday in the Zambian capital of Lusaka before flying to Tanzania. "And when you leave, you don't leave much behind for the people who are there. We don't want to see a new colonialism in Africa."