The current COVID-19 outbreak is the biggest challenge for the world since World War Two, UN Secretary General António Guterres has warned.

He said it could bring a recession "that probably has no parallel in the recent past", BBC reports.

His warning comes amid dire predictions about the possible economic impact of measures imposed to fight the virus.

The number of confirmed cases around the world is now nearing 860,000, with more than 42,000 deaths.

Mr Guterres urged the industrialised nations to help those less developed, or potentially "face the nightmare of the disease spreading like wildfire".

On Tuesday, the World Bank warned that "significant economic pain" seemed "unavoidable in all countries", and households that depend on industries particularly vulnerable to the impact of the virus were at "higher risk".

Meanwhile, US President Donald Trump told Americans to prepare themselves for "a very, very painful two weeks", as modelling by the White House's coronavirus task force estimated that at least 100,000 could die in the coming months.