A White House event held to celebrate the nomination of a Supreme Court justice was a “dangerous situation”, top US virus expert Anthony Fauci has said.

The September 26 ceremony in a crowded White House Rose Garden is feared to have been a “super-spreader” event as a growing number of senior Republicans have tested positive for Covid-19.

Footage showed many guests were not wearing masks or sitting two metres apart and they were hugging, shaking hands and bumping fists.

Dr Fauci, head of the National Institute of Allergy and Infectious Diseases, told Times Radio: “When I see pictures like that, not only there but anywhere, people who are in bars congregating, people who are at parties congregating without masks, that is a dangerous situation that can lead to a high risk of transmissibility, and unfortunately, and I say really unfortunately, that’s exactly what happened during that meeting that was had to celebrate the appointment of a Supreme Court justice.”

Dr Fauci restated the need to stick to “the fundamental tenets of public health” in dealing with Covid-19, which include wearing masks, keeping distance, avoiding crowds, doing things outdoors more than indoors, and frequent handwashing.

Mr Trump formally announced his nomination of the conservative Amy Coney Barrett for the Supreme Court on September 26, then tweeted on Friday that he and his wife had tested positive for Covid-19.

The president was treated in hospital for three days after being admitted with Covid-19.

The White House has become the epicentre of a coronavirus outbreak.

Mr Trump, his wife, former top aide Kellyanne Conway, former New Jersey governor Chris Christie, University of Notre Dame president John Jenkins, senators Mike Lee and Thom Tillis and a White House reporter are among those who have tested positive since attending the nomination event.

It can take around five to six day for symptoms to start after contracting the virus, according to the World Health Organisation.

On whether the White House event could be considered a “super-spreader”, Dr Fauci told the programme: “We haven’t done all of the precise epidemiology. But I agree with you, if you look at it, and some of the people that were all commonly there, that it looks like that that could have been an event where there was multiple people infected.”