A new World Bank report says economic growth across sub-Saharan Africa is projected to fall to 1.6 percent in 2016, the lowest level in more than two decades. Growth was 3 percent last year.

The report released Thursday says the weak growth mainly reflects the deteriorating performance of the continent's largest economies, Nigeria and South Africa. Together, they account for half the region's economic output.

The report notes, however, that some countries such as Senegal and Ethiopia are posting annual growth rates surpassing 6 percent.

The World Bank sees growth in sub-Saharan Africa rising to 2.9 percent in 2017.

The report analyzing the state of African economies is issued twice a year.