A top World Health Organization official said on Monday that the WHO cannot compel China to divulge more data on COVID-19's origins, while adding it will propose studies needed to take understanding of where the virus emerged to the "next level".

Pressed by a reporter on how the WHO will "compel" China into being more open, Mike Ryan, director of the agency's emergencies programme, said at a press conference that the "WHO doesn't have the power to compel anyone in this regard".

"We fully expect cooperation, input and support of all of our member states in that endeavour," Ryan said.

There are competing theories: that the virus jumped from animals, possibly starting with bats, to humans, or that it escaped from a laboratory in Wuhan, China. Members of a WHO team that visited China earlier this year hunting for COVID-19's origins have said they did not have access to all data, fueling continued debate over the country's transparency.