Dr Peter Ben Embarek, head of the World Health Organisation investigation, explained the theory in a new documentary airing on Danish television channel TV2. China has continue to strenuously deny the virus originated from one of its laboratories.

       At least 4.3 million people have died since it was first identified in the city of Wuhan in December 2019.

       In March 2021, the first part of the WHO investigation concluded that the lab leak theory was "extremely unlikely".

       But Dr Embarek explained why the theory is valid.

       He said: “An employee who was infected in the field by taking samples falls under one of the probable hypotheses.

       “This is where the virus jumps directly from a bat to a human.

       “In that case, it would then be a laboratory worker instead of a random villager or other person who has regular contact with bats.

       “So it is actually in the probable category.”

       In January, Dr Embarek led a team of experts on the first phase of the WHO-directed investigation which focused on working with local officials in China to find the origin of the global health crisis.

       READ MORE: Delta Covid variant map: Why mix and match vaccines are key to control

       Dr Embarek alleged Chinese officials and scientists were difficult to talk to about the lab leak hypotheses.

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