The White House has ruled out introducing mandatory federal Covid-19 vaccination passports, saying citizens' privacy and rights should be protected.

Schemes to introduce such passports have been touted around the world as a way to enable safe circulation of people while fighting the pandemic.

But critics say such documents could be discriminatory.

The US said it did not and would not support a "system that requires Americans to carry a credential".

The country has reported more than 550,000 deaths linked to the virus and nearly 31 million cases, the highest numbers in the world, according to Johns Hopkins University.

Addressing reporters, White House press secretary Jen Psaki said there would be no "federal vaccinations database" or a "federal mandate requiring everyone to obtain a single vaccination credential".

"The government is not now, nor will be, supporting a system that requires Americans to carry a credential," she said. "Our interest is very simple from the federal government, which is Americans' privacy and rights should be protected, and so that these systems are not used against people unfairly."

Countries around the world are looking at the introduction of so-called vaccine passports, which would be used to show that a person has been inoculated against Covid-19, as a way of safely reopening mass gatherings and travel.

In England, a "Covid status certification" scheme is being developed to enable concerts and sports matches to take place. It would record whether people had been vaccinated, recently tested negative, or had already had and recovered from Covid-19.

The European Union is also working on plans to introduce certificates, while in Israel a "Green Pass" is already available to anyone who has been fully vaccinated or has recovered from Covid-19, which they have to show to access facilities such as hotels, gyms or theatres.

The World Health Organization on Tuesday said it did not currently support requiring vaccination passports for travel, because of uncertainty over whether inoculation prevents transmission, and discrimination concerns.

Meanwhile, US President Joe Biden announced on Tuesday that he had brought forward to 19 April the date by which all American adults will be eligible for a Covid vaccine.

"We have to ramp up a whole-of-government approach that rallies the whole country and puts us on a war footing to truly beat this virus," he said.