The economy of sub-Saharan Africa will grow more slowly this year than previously forecast.

And this is due to due to weak investment and productivity, the World Bank said on Wednesday.

In a report, it forecast growth in the region to be 2.4% in 2017, down from the 2.6% that it projected in April. But growth was seen rising to 3.2% in 2018 and 3.5% in 2019, forecasts unchanged from earlier this year.

In its latest Africa Pulse report, the Bank said the region would be helped by better commodity prices. Lower prices have slowed overall growth in the resource-rich region in the last few years, cutting government revenues.

Sub-Saharan Africa’s growth was an estimated 1.3% in 2016, the lowest for two decades.

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The Bank said the downgrade to 2017 projections was due to various conditions, including the failure of Nigeria - which has Africa’s biggest economy - to meet expectations.

“Regional per capita output growth is forecast to be negative for the second consecutive year, while investment growth remains low, and productivity growth is falling,” it said.

Nigeria escaped from its first recession in 25 years in the second quarter as oil revenues rose following the cessation of militant attacks on energy facilities in the Niger Delta that last year cut crude production by around a third.

However, the pace of growth was slow.

The Bank said Nigeria’s expected 1% growth in 2017 was 0.2 percentage points below the April forecast because the increase in oil production was below projections due to maintenance work. It said growth in the non-oil sector has remained subdued.

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