The head of the World Health Organisation privately believes the Covid pandemic started following a leak from a Chinese laboratory, a senior Government source claims.

While publicly the group maintains that ‘all hypotheses remain on the table’ about the origins of Covid, the source said Tedros Adhanom Ghebreyesus, director-general of the World Health Organisation (WHO), had recently confided to a senior European politician that the most likely explanation was a catastrophic accident at a laboratory in Wuhan, where infections first spread during late 2019.

The Mail on Sunday first revealed concerns within Western intelligence services about the Wuhan Institute of Virology, where scientists were manipulating coronaviruses sampled from bats in caves nearly 1,000 miles away – the same caves where Covid-19 is suspected to have originated – in April 2020. The worldwide death toll from the Covid pandemic is now estimated to have hit more than 18 million.