British spies believe that the thesis that COVID-19 leaked from a lab in China is plausible and are seeking to recruit sources on the darknet as they investigate the claim, reported The Sunday Times.

Sources told the publication that while UK intelligence was initially highly skeptical of the theory that the disease escaped from the Wuhan Institute of Virology, they now believe the theory is “plausible.”

But intelligence agents, according to the report, have few human sources of information in China, so they are trying to recruit them on the darknet, where they can speak anonymously without fear of reprisal.

In recent weeks information has emerged suggesting that the virus, which has spread across the globe, killing more than 3 million in the worst pandemic for generations, may not have developed from nature, as scientists initially believed.

The lab leak theory, pushed by President Donald Trump to score points against Beijing, was initially dismissed as a conspiracy theory by many.

After visiting Wuhan earlier this year in a report released with Chinese scientists, scientists from the World Health Organization said the theory that the virus escaped from a lab is improbable.

Many scientists believe that the virus crossed from animals, likely bats via another species, to humans in a market in Wuhan. But defenders of the lab-leak theory have pointed out that the Wuhan virology institute is one of the world’s leading research centers into bat coronaviruses.

The Wuhan lab is a short distance from where the first COVID-19 cases were recorded in November. The Wall St Journal has reported that scientists from the lab had fallen sick with an illness and been hospitalized in November 2019, weeks before the first official cases.

With the new debate about the possible source of the virus, US President Joe Biden has ordered a 90-day review of intelligence into the origins of the coronavirus to establish its source.