US President Donald Trump has announced new government recommendations for all Americans to wear masks when they go outside to help to stop the spread of the Covid-19.

Mr Trump told a White House press conference that the Centers for Disease Control and Prevention was urging people to wear any face covering, like scarves, but to keep medical-grade masks free for health workers.

In a daily briefing with reporters, Mr Trump stressed that the new recommendation should not be seen as replacing social distancing measures, considered key to slowing the outbreak.

"With the masks, it's going to be really a voluntary thing. You can do it, you don't have to do it. I'm choosing not to do it, but some people may want to do it and that's OK," said President Trump.

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The decision to promote mask use comes as state governors and hospitals clamour for scarce supplies of medical grade masks for first responders.

It also comes as experts have questioned the administration's decision not to urge widespread mask use, in contrast to other countries hit by the virus.

Covid-19 has now claimed more lives in New York state than the 11 September 2001 attacks.

Nationwide, almost 1,500 deaths were recorded between Thursday and Friday, according to the Johns Hopkins University tracker, the worst 24-hour death toll globally since the pandemic began. 

With 1,480 deaths counted between 8:30pm Thursday and the same time Friday, according to the university's continuously updated figures, the total number of people who have died since the start of the pandemic in the United States is now 7,406.