There is mounting criticism over the World Health Organization’s(WHO) team of researchers failing to determine the origin of COVID-19 from their investigation in Wuhan, China.

On Tuesday, the team of Chinese and international experts said the virus spread both inside and outside the Huanan Seafood Market in Wuhan in December 2019, suggesting that the market was not necessarily the original source.

They suggested that the virus jumped across species in nature through intermediary hosts such as pangolins, cats or minks.

The team also dismissed as "extremely unlikely" a theory that the virus leaked from laboratories at the local Wuhan Institute of Virology(WIV), adding that they were satisfied with how the institute answered their questions about safety.

According to the Washington Post, Marc Lipsitch, a professor of epidemiology at Harvard's T.H. Chan School of Public Health, stressed that simply stating that the WIV has really good safety protocols alone does not put his mind at rest.

David A. Relman, a microbiologist at Stanford University, said if the only available information is provided by the very people who have everything to lose by revealing such evidence, it “doesn't come close to passing the sniff test.”

Relman suggested that the WHO team should have sought complete, detailed records from the laboratories about their experiments and the raw genomic sequence data of their research going back a decade.