GDP for 2013 totalled 80.3 trillion naira (£307.6bn: $509.9bn), the Nigerian statistics office said.
That compares with South Africa’s GDP of $370.3bn at the end of 2013.
However, some economists point out that Nigeria’s economic output is underperforming because at 170 million people, its population is three times larger than South Africa’s.
On a per-capita basis, South Africa’s GDP numbers are three times larger than Nigeria’s.
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