A further 86 cases of the new Omicron COVID variant have been reported in the UK, taking the total to 246.
This compares with a total of 160 yesterday – an increase of more than 50%.
The UK Health Security Agency, which publishes the figures, says 18 of the cases are in Scotland, taking its total up to 48.
The figures come as one expert told Sky News the UK could face “more stringent measures” after Christmas to counter the spread of the new variant.
Professor Sir David Spiegelhalter said the emergence of Omicron in the UK was “appalling timing” as the next few weeks are “one of the highest risk periods… with a lot of indoor socialising”.
He said that the government “would love not to disrupt Christmas”, but he warned: “What happens after Christmas is another matter.”
Although the UK is still waiting for real-world data on the new variant, Professor Spiegelhalter, a statistician at the University of Cambridge, said that currently it does not appear to have as much of a risk of severe disease.
And he also praised the booster vaccines for “saving very large numbers of lives”.
Deputy Prime Minister Dominic Raab also told Sky News: “The government wants people to enjoy Christmas this year”, adding that employers should take a “common sense” approach to office parties.
And there are warnings the NHS will be in a “very, very difficult position” if the Omicron variant were to lead to a surge in hospital admissions.
The president of the Royal College of Emergency Medicine, Dr Katherine Henderson, said hospitals were already struggling to cope as they enter winter.
“It is pretty spectacularly bad now, it will get worse – and if the new variant becomes a thing in terms of numbers and translates into hospitals admissions we are going to be in a very, very difficult position,” she said.
“We will always still be there. We still want patients to come but we do have to help people to understand that really at the moment the service is so stretched that an extra push could be very very difficult.”