The United States shared “gobsmacking” evidence with Britain at the height of the Covid-19 pandemic that suggested a “high likelihood” that the virus had leaked from a Chinese lab, The Telegraph can reveal.

Five Eyes intelligence-sharing nations were convened in Jan 2021 to discuss the possibility of a “lab leak”, as the US warned that China had covered up research on coronaviruses and military activity at a laboratory in Wuhan.

In a previously unreported phone call in Jan 2021, Mike Pompeo, the former US secretary of state, presented evidence that supported the lab leak theory to his counterparts, Dominic Raab, then the Foreign Secretary, and representatives from Canada, New Zealand and Australia.

Speaking to The Telegraph, two Trump administration officials accused Mr Raab and the UK government of ignoring the lab leak theory because of resistance from government scientists who supported the explanation that the virus had jumped between animals and humans.

Mr Pompeo presented a summary of classified American intelligence reports collected in the early days of the pandemic and compiled by the State Department. The intelligence reports themselves are understood to have been shared separately with the UK via the Five Eyes network between Oct and Dec 2020.

“We saw several pieces of information and thought that they were, frankly, gobsmacking,” said one former official who worked on the intelligence that informed Mr Pompeo’s report. “They obviously pointed to the high likelihood that this was indeed a lab leak.”

In one document, which has since been released by the State Department under Freedom of Information laws, US officials warned of “consistent stonewalling” by China after the virus was first discovered and accused local officials of “gross corruption and ineptitude”.

The research revealed for the first time that Chinese military officials had worked with the Wuhan Institute of Virology (WIV) in the years leading up to the pandemic, and that some researchers at the lab had become ill shortly before the virus was first recorded nearby.

It also showed that Chinese scientists had carried out “gain of function” research at the WIV, which has since become a key piece of evidence for the lab leak theory pushed by its supporters.

The theory has become a divisive topic among scientists and government officials in the years following the pandemic and has prompted two investigations by the World Health Organisation, which China has been accused of obstructing.

British government ministers, including Boris Johnson, initially dismissed the possibility that Covid-19 had been created by scientists, arguing in June 2021 that “the advice that we have had is that it doesn’t look as though this particular disease of zoonotic origin came from a lab”.

Two former officials claimed that the UK had ignored the evidence presented by the US because ministers saw the lab leak claims as a “radioactive American political issue” fuelled by public disagreement between government scientists and Mr Trump.

“Once the thing became fundamentally political, the ability to pursue it internationally really just collapsed because no one else was interested in touching it,” said one of the officials.

“I think [Five Eyes] were kind of annoyed by the way the issue had become treated in US politics.”

Both separately named Jeremy Farrar, a member of the government’s Scientific Advisory Group for Emergencies as one of the leading opponents of the lab leak theory within the British government.

A majority of scientific experts have long said that they believe an animal-to-human interaction was the most likely cause of the first infection.

However, some government figures, including Michael Gove, have since said that they believe the virus was “man-made”.

Mr Gove told the Covid Inquiry in November that there was a “significant body of judgement that believes that the virus itself was man-made – and that presents its own set of challenges”.

Both the FBI and US Department of Energy have said they believe a lab leak is the most likely cause of Covid-19, while other agencies have said they think it occurred naturally.

Joe Biden, the US president, has said he does not know where the virus started, while the US National Intelligence Council said last year it “probably emerged and infected humans through an initial small-scale exposure”.

UK ministers are now facing calls to expand the terms of the Covid Inquiry to include an investigation into the origin of the virus.

The Telegraph understands that the call in Jan 2021 was deliberately held on an “open line” without security encryption in the hope that Chinese intelligence agencies would hear that Western countries were aware of military activity in Wuhan.

“We did that deliberately…we wanted to put pressure on the bad guys,” said a State Department source.

Ten days after the call, in which officials said the UK was unwilling to assist with a US-led lab leak investigation or share its own research, the summary compiled by Mr Pompeo’s officials was released to the public in a “fact sheet”.

Those involved in the release said they took care to avoid revealing the sources or methods of US spy agencies, and that it was just the “tip of the iceberg” of the underlying intelligence that had been gathered.

A UK government spokeswoman said: “There are still questions that need to be answered about the origin and spread of Covid-19, not least so we can ensure we are better prepared for future pandemics.

“The UK continues to support the World Health Organisation in its expert study of the origins of Covid-19. It is important that China and other countries cooperate fully with the researchers.”