Officials warned it would “cause problems” if he repeated the claim in his Pandemic Diaries and insisted he must make clear he was not reflecting the Government’s view, The Daily Telegraph reported.
The changes to the book were made after he submitted the manuscript to the Cabinet Office for review last year – a procedure all former ministers are obliged to follow.
According to the Telegraph, which has obtained tens of thousands of the former health secretary’s messages, Mr Hancock had wanted to say that “given how cagey the Chinese have been” their official version of events should be treated with “considerable scepticism”.
This is highly sensitive and would cause problems if released
“Global fear of the Chinese must not get in the way of a full investigation into what happened,” he wrote in the original manuscript.
In response, the Cabinet Office wrote: “This is highly sensitive and would cause problems if released.
“Must be clearer that it is supposition rather than revealing any confidential information received from inside government. Should also be clear that this is not HMG views or beliefs.”
It also expressed concern about proposed comparisons in the book between the Wuhan Institute of Virology – in the city where the virus first emerged – and the Ministry of Defence’s research laboratories at Porton Down.
Mr Hancock originally wrote it was “just too much of a coincidence” that the pandemic started in the same city as the institute.
“The only plausible alternative is that the virus was brought to Wuhan to be studied, and then escaped,” he wrote in one passage.
“The Chinese denials are a bit like us claiming that a random virus just happened to break out near a little place called Porton Down, perhaps because of some badgers. It just doesn’t fly.”
However the Cabinet Office expressed concern that it could be seized on by the Russians, who had previously claimed the novichok nerve agent used in the Salisbury poisoning of Sergei and Yulia Skripal originated at Porton Down.
“The reference to Porton Down is damaging to national security – what is set up as a joke, is one of the attack lines Russia has used against us for the novichok poisoning, as it is only a few miles from Porton Down to Salisbury (which is entirely coincidental – as, we believe, it is that the Wuhan lab is so close to where the first Covid outbreak was recorded),” it said.
The disclosure comes after the head of the FBI said last week the agency had assessed that Covid was “most likely” the result of a lab leak.
In response to the Telegraph report, a Government spokesman said: “We would not comment on leaks or private discussions.”
A spokesperson for Mr Hancock said: “Matt will categorically not comment on national security matters.
“The release of this material shows yet again that this unlawful leak of partial information is motivated only by money and an attempt to spin a biased narrative.
“This is completely against the public interest, which will be served by the public inquiry.”