WASHINGTON — The Obama administration sought Monday to strengthen ties with Africa at an unprecedented summit with dozens of African leaders, grappling with issues such as investment, poverty, terrorism, corruption and deadly diseases.

Nearly 50 African heads of state attended the gathering focused on how to build democracy and raise investment in the continent.

Top U.S. officials spoke positively about U.S.-Africa relations and progress on the continent.

“I think something like 10 of the 15 fastest-growing countries in the world are in Africa,” Secretary of State John Kerry said. “Africa will have a larger workforce than India or China by 2040.”

The Obama administration says it is committed to renewing the Africa Growth and Opportunity Act, which is set to expire next year. Since 2000, AGOA has been at the center of the U.S. efforts to promote trade and investment in Africa while opening new sources of material for U.S. producers.