There were a wide range of possibilities for how trade would be hit by the "unprecedented" health crisis, it added.

However, WTO chief Roberto Azevedo warned the downturn "may well be the deepest economic recession or downturn of our lifetimes".

In its main annual forecast, the 164-member WTO pointed out that trade had already been slowing in 2019, before the emergence of the novel coronavirus.

But the virus has now infected some 1.4 million people since late last year, killing more than 80,000 and forcing governments across the world to take radical measures.

More than half of humanity has been asked to stay at home and economic activity has ground to a virtual standstill in many places.

Global trade, already hit by trade tensions and uncertainties around Brexit, is expected to register "double-digit declines in trade volumes" in nearly all regions this year, the WTO said.

"This crisis is first and foremost a health crisis which has forced governments to take unprecedented measures to protect people's lives," Azevedo said in a statement.

"The unavoidable declines in trade and output will have painful consequences for households and businesses, on top of the human suffering caused by the disease itself," he said.