China has issued repeated denials that it is the source of the virus.
Scientists who supported the lab theory have been repeatedly shouted down by colleagues and scientific journals who claim the virus jumped from animals to humans.
Previously, western intelligence services believed there was only a “remote” chance the virus had originated in the lab, which studies bat-derived coronaviruses.
They now believe the lab theory is “feasible”, according to the Sunday Times.
Covid-19 has killed around 3.5 million people worldwide.