Emerging nations’ drive to catch up with the incomes of the developed world has been set back decades by the slowdown in their economies and the impact of the commodities slump, according to World Bank research.

The bank on Tuesday downgraded its global growth forecast because of what it said was a much worse than expected performance by commodity-exporting countries. It expects the global economy to grow 2.4 per cent this year, compared with a previous forecast of 2.9 per cent, with emerging commodity exporters as a group set to expand just 0.4 per cent — down from 3.2 per cent as recently as 2013.

That downgrade came alongside a new analysis showing that for the first time since the turn of the century a majority of emerging and developing economies were no longer closing the income gap with the US and other rich countries.