The UN has warned that the economic downturn due to the pandemic could wipe out the gains of the last four years, at a cost of $8.5 trillion (£6.9 trillion) in economic activity.

Its assessment of global prospects says that more than 30 million people are likely to fall into extreme poverty this year, mainly in Africa.

The UN expects the rich economies to shrink more at 5%, but for the developing world even the more moderate decline predicted means a marked increase in poverty.

For many of those countries, the report says, the costs of fighting the pandemic and economic stimulus measures will be prohibitive.

It also says governments in developing countries are spending an ever-increasing share of their revenue on debt interest.

Separately a group of leading politicians, including the former US presidential candidate Bernie Sanders, has called for the cancellation of some of the debts owed by the poorest countries.