Leaders of the African Union have begun a three-day summit during which they are expected to address the situation in Darfur and the issue of African unity.

Police monitored the streets of Accra, Ghana, as more than 30 heads of state gathered for the summit.

The agenda includes discussion of the idea of a United States of Africa.

Proponents of the plan argue a federation of African nations could exercise more influence and better address problems facing the world's poorest continent. But regional powers like South Africa favor a more gradual consolidation of regional economic groups.

The idea of a united Africa was conceived four decades ago by Ghana's first president, Kwame Nkrumah.

Some information for this report provided by AP and AFP.