America’s top infectious diseases expert, Dr Anthony Fauci, says he did not sign off on an ad spruiking President Donald Trump’s handling of the pandemic.

“In my nearly five decades of public service, I have never publicly endorsed any political candidate,” Dr Fauci said in a statement on Sunday (US time).

“The comments attributed to me without my permission in the GOP campaign ad were taken out of context from a broad statement I made months ago about the efforts of federal public health officials.”

The ad was released last week, shortly after Mr Trump was discharged from Walter Reed National Military Medical Centre. It discusses the President’s effort to personally recover from the coronavirus, as well as his administration’s work to address the pandemic.

The 30-second election campaign ad uses older remarks from Dr Fauci, edited to make it sound as if he is praising the President.

“I can’t imagine that anybody could be doing more,” Dr Fauci says in the ad.

Watch the controversial ad

But those remarks are from March, when Dr Fauci, who has been director of the National Institute of Allergy and Infectious Diseases since 1984, was discussing the broader effort, including by the White House coronavirus task force.

On Sunday, Dr Fauci said he didn’t agree to be featured in an ad for Mr Trump’s campaign and his comments were taken out of context.

Campaign spokesman Tim Murtaugh insisted the words were “accurate and directly from Dr Fauci’s mouth”.

“As Dr Fauci recently testified in the Senate, President Trump took the virus seriously from the beginning, acted quickly and saved lives,” Mr Murtaugh said.

Tweet from @realDonaldTrump

Dr Fauci and Mr Trump have not always agreed on how to handle the pandemic, which has infected nearly 7.7 million people in the US, killing more than 214,000.

Opinion polls show most voters disapprove of the President’s handling of the crisis.

‘Super-spreader event’: The White House ceremony to introduce Amy Coney Barrett.

On Friday, Dr Fauci described the September 26 White House ceremony to introduce Supreme Court nominee Amy Coney Barrett, after which several attendees including Mr Trump, tested positive, as a “super-spreader event”.

ABC News said on Sunday it had asked the White House to allow Dr Fauci to appear on The Week but the administration refused to make him or other task force members available.

-with AAP