Sky News host James Morrow says Republican Rand Paul "wasn't having any of Dr Fauci's attempts to redefine gain-of-function research" as the senator proceeded to "demolish" his claims amid a "pretty testy" exchange this week in US Congress.

Mr Morrow said Senator Paul accused Dr Anthony Fauci, the "liberal left's secular saint" of the pandemic, of "lying" to cover up his role as head of America's National Institutes of Health in "funding" coronavirus research at the Wuhan Institute of Virology.

Dr Fauci rejected Senator Paul's claims on the grounds what was conducted at the labs had been judged by "qualified staff up and down the chain" as not being "gain-of-function" research.

Mr Morrow said Senator Paul "demolished" these claims by saying viruses "in nature that only infect animals were manipulated in the Wuhan lab to 'gain the function' of infecting humans".

"We know from Dr Fauci's own emails that from the very start of the pandemic he was concerned that gain of function research his agency was associated with could have been responsible for the pandemic," Mr Morrow said.

"After the exchange, Senator Paul said he was going to ask the Department of Justice for a criminal referral into Fauci, and whether he lied to Congress.

"It may not be possible to bring back those lives or livelihoods lost to the pandemic, but there may just be some justice for them after all."