England's former deputy Chief Medical officer Prof John Watson, who was part of the WHO delegation team sent to Wuhan to investigate the sources of the pandemic, said he was not certain about COVID-19 originated in China.

He said it is possible that the virus's leap from animals to humans could have happened outside China.

The pandemic most likely started with an infection in an animal reservoir and then passed on to humans through an "intermediate host," he told on BBC One's Andre Mar Show.

"I think that there are all sorts of reasons to do with the way it did start in the outbreak in Wuhan and the various bits of information about the way in which these viruses live in different animal reservoirs, that suggest that China is a very, very possible source for the outbreak, but by no means necessarily the place where the leap from animals to humans took place. And I think we need to ensure that we are looking beyond the borders of China, as well as within China," Professor John Watson said.

Washington has been blaming China for hiding the early findings and not letting the WHO team, full access to raw data.

The WHO, however, has denied the allegations of the US. Professor Watson said they saw a great deal of information about the cases.