Cases of the new Omicron Covid-19 variant have reportedly risen by more than half in just one day.
A further 86 cases have have been reported in the UK, taking the total number to 246.
Yesterday that figure was 160, a rise of more than 50 percent.
And 68 of those new recorded cases have been identified in England.
The UK Health Security Agency (UKHSA) says 18 of the cases are in Scotland, taking its total up to 48.
In a daily tweet, the UKHSA confirmed: "86 additional confirmed cases of the #Omicron variant of COVID-19 have been reported across the UK with 68 in England.
"The total number of confirmed COVID-19 cases is now 246."
READ MORE: Scientists warn UK government to 'act now' on Omicron.
It comes as a Government science adviser warned it is “too late” to effectively halt the spread of the Omicron variant in the UK.
On Saturday, it was announced all travellers arriving in England will be required to take a Covid-19 pre-departure test from Tuesday – while Nigeria is being added to the Government’s travel red list.
Ministers said the extra test was intended to be a temporary measure following new data showing an increase in the number of cases of the new strain linked to foreign travel.
But Professor Mark Woolhouse, who is a member of the Scientific Pandemic Influenza Group on Modelling (Spi-M) which advises the Government, said the measures would not make a “material difference” as the variant is already “spreading pretty rapidly”.
It comes as students and teachers at a Bolton school were told they were to undergo special testing after a reported case of Omicron was uncovered at the school.
READ MORE: ' Highly probable' Omicron Covid-19 case discovered at Bolton primary school
There remains concerns about the increased socialising at Christmas and the threat posed by the new Omicron variant of coronavirus.
But Deputy Prime Minister Dominic Raab told Sky News: "The government wants people to enjoy Christmas this year", adding that employers should take a "common sense" approach to office parties.
The Omicron variant is “spreading pretty rapidly” in the UK, a Government science adviser has said
However Professor Mark Woolhouse, who is a member of the Scientific Pandemic Influenza Group on Modelling (Spi-M), told the BBC’s Andrew Marr show: “The Omicron variant is highly transmissible, it appears to be spreading very rapidly in South Africa and the early signs are that it’s spreading pretty rapidly in the UK too.
“If those trends continue then over the course of the coming weeks and months, Omicron could even come to replace Delta entirely right around the world."
