Reports that British agents believe it is “feasible” the coronavirus pandemic began with a leak from a Chinese research laboratory in Wuhan have led to renewed calls for the World Health Organisation (WHO) to be allowed to fully investigate the origins of the outbreak.
The Sunday Times reported that the development, which Beijing has angrily denied, has prompted US diplomatic sources to share their concerns that “we are one wet market or bio lab away from the spillover”.
What is the UK government’s stance?
The UK’s vaccines minister, Nadhim Zahawi, told Sky News: "I think it's really important that the WHO is allowed to conduct its investigation unencumbered into the origins of this pandemic and that we should leave no stone unturned to understand why, not only because of the current pandemic that has swept the world, but also for future-proofing the world's capability to deal with pandemics."
Mr Zahawi was asked if he could trust the WHO after a team of experts from WHO and China said in February the virus was "extremely unlikely" to have entered the human population as a result of a laboratory-related incident, and was instead probably transmitted from bats to humans through another animal.
Dr Tedros Adhanom Ghebreyesus, director general of the WHO, has said he did not believe the initial report was "extensive enough" and called for more research, adding that all hypotheses into the origins of the virus that causes Covid-19 "remain on the table".
Mr Zahawi said: "I think the WHO at every step of the way has tried to share as much data with the world as it is able to verify.
"This is a very difficult situation, as we've seen around the world, not just in the WHO but in our own country, with our own evidence gathering and, of course, advice and in other countries, every country, whether it's Singapore or Australia or New Zealand or elsewhere.
"We have all had to collect evidence and then act upon it and I think it is only right that the WHO is allowed to conduct its investigation unencumbered to be able for all of us to understand and be able to deal with future pandemics.”
What do the experts think?
Professor Dale Fisher, part of the WHO team that visited China, said the lab leak theory had not been ruled out but there was little evidence for it.
"China has had many instances where there has been whistleblowers before and to me that's another striking point here, is that there is no whistleblower," he told BBC Radio 4's The World This Weekend.
"So, in fact, the only evidence in my mind for there being a lab leak is that there was a lab."
He added: "The lab leak theory is not off the table, there's more research to be done."
Charles Parton, a former diplomat who worked in China and senior associate fellow at the Royal United Services Institute (Rusi), told Times Radio that if the virus had escaped a lab it would have been an accident.
He suggested efforts should be made to "keep the temperature down whatever is discovered".
He added: "It may be that scientists are clever enough without access to Chinese laboratory records to work out fairly conclusively over time how it came to come out and maybe it was a leak.
"If that's the case, and it's a big if, we should nevertheless not be too blaming because we have got to look to the future and try to get Chinese cooperation."
He said measures such as "UN nuclear inspection mechanisms" should be in place to monitor laboratories.
"I think in the immediate aftermath of this pandemic it's going to be a very sensitive matter to set that up because the Chinese will see that as an accusation of fallibility," he said.
What reignited theories about the Wuhan lab leak?
It comes after the US president, Joe Biden, ordered his intelligence officials to "redouble" their efforts to investigate the origins of the pandemic, including any possibility the search might lead to a Chinese laboratory.
On Wednesday, Mr Biden asked US intelligence agencies to report back within 90 days, and he said that he aimed to release their results publicly.
His remarks prompted the WHO’s top emergency expert, Mike Ryan, to say the search for the origin of the outbreak was being “poisoned by politics”.
"We would like for everyone out there to separate, if they can, the politics of this issue from the science. This whole process is being poisoned by politics," Mr Ryan said on Friday.
"Every country and every entity is free to pursue their own particular theories of origin, it's a free world," Mr Ryan said. "WHO is a member state organisation and we seek to work with all of our member states to seek answers collectively."
Lawrence S Young, virologist and professor of molecular oncology at Warwick Medical School, said: “It is important that WHO have unfettered access to laboratory records from the Wuhan Institute of Virology.
“While the balance of scientific evidence remains in favour of animal spillover, the possibility of an unintentional release from a laboratory working on coronaviruses needs to be thoroughly investigated otherwise the current speculation will never be dispelled.
“It is vital that we fully understand the origin of SAR-CoV-2 to ensure that we can do everything to prevent another pandemic in the future.”