US President Joe Biden has announced new pandemic requirements aimed at boosting vaccination rates for millions of federal workers and contractors, as he lamented the "American tragedy" of deaths among the unvaccinated.
Federal workers will be required to sign forms attesting they have been vaccinated against the coronavirus or else comply with new rules on mandatory masking, weekly testing, distancing and more.
The strict new guidelines are aimed at increasing sluggish vaccination rates among the huge number of Americans who draw federal pay cheques - and to set an example for private employers around the country.
Biden said at the White House: "Right now, too many people are dying or watching someone they love die and say: 'If I'd just got the vaccine.'"
"This is an American tragedy. People are dying who don't have to die."
However, Biden is certain to meet resistance. His comments put him squarely in the centre of a fierce political debate surrounding the government's ability to compel Americans to follow public health guidelines.
The federal government directly employs about four million people, but Biden's action could affect many more when federal contractors are factored in.
New York University professor of public service Paul Light estimates there are nearly seven million more employees who could potentially be included, combining those who work for companies that contract with the government and those working under federal grants.
Biden has also called for state, local and US territorial governments to provide $US100 ($A135) payments for every newly vaccinated person to boost COVID-19 inoculation rates.
The US Treasury Department said in a statement that such incentives are an allowable use of funds from the $US350 billion in aid granted to state, local, territorial and tribal governments under the American Rescue Plan Act.
Biden, seemingly fed up with persistent vaccine resistance among many Americans, delivered a sharp rebuke to those who have yet to get their jabs, saying "they get sick and fill up our hospitals", taking beds away from others who need them.
"If in fact you are unvaccinated, you present a problem to yourself, to your family and those with whom you work," he said bluntly.
His comments came as some 60 per cent of American adults have been fully vaccinated.
The US leader had set a July 4 goal to get at least one jab in 70 per cent of adults, and is still not quite there. The latest figure is 69.3 per cent. And there remains significant resistance from many Republicans and some unions to vaccine mandates for employers.
Biden also directed the US defence department to look into adding the Covid-19 jab to its list of required vaccinations for members of the military.
Service members already are required to get as many as 17 vaccines, depending on where they are based around the world.
Australian Associated Press