Workers in protective suits set up barriers outside a building, following the coronavirus disease (COVID-19) outbreak, in Shanghai, China June 9, 2022. (Photo: REUTERS)

The report from the WHO expert panel said all available data showed the novel coronavirus that causes COVID-19 probably came from animals, likely bats, a similar conclusion to the UN agency's previous work on the topic in 2021 that followed a trip to China.

The missing data, especially from China, where the first cases were reported in December 2019, meant it was not possible to identify exactly how the virus was first transmitted to humans.

The findings are likely to add to doubts it will be possible to determine how and where the virus emerged. They will also inject urgency into the effort to overhaul the WHO and its health emergency procedures as the agency strives to reassert itself after years of criticism over its handling of the pandemic.