The US will eventually require almost all foreign visitors to be fully vaccinated, a White House official has said.

The unnamed official told several news agencies that the Biden administration had tasked inter-agency groups with creating a phased reopening for international visitors.

No timeline for the decision was given.

The US has seen a rise in cases, particularly among the unvaccinated, amid the spread of the Delta variant.

Current Covid-19 rules prevent most international travellers from entering the country.

The first round of travel restrictions were imposed on China in January 2020.

Since then, the US ban has expanded to include non-US citizens who had recently visited the UK, the 26-nation Schengen bloc in Europe, Brazil, Ireland, India, Iran and South Africa.

Those who are able to enter the country must show proof of a negative Covid test taken within three days of travel.

Last week, White House Press Secretary Jen Psaki said that the US would "maintain existing travel restrictions at this point" due to rising infections, despite opposition from airlines and the tourism industry.

On Wednesday, the unnamed White House official said the administration was looking to reopen in a "safe and sustainable manner", adding that "with limited exceptions... foreign nationals travelling to the United States - from all countries - need to be fully vaccinated".

It is not clear if that requirement would mean only US-approved vaccines would be accepted. The Astra-Zeneca jab has not yet been approved in the US.

More than 70% of American adults have received at least one dose of the Covid-19 vaccine.

However, cases are rising in a number of states, with a record number of hospitalizations in Florida, according to officials.

Many regions and businesses across the US are once again introducing rules to force people to wear masks in public places.