The UK has recorded 448 new Omicron cases in the latest 24-hour period – taking the total across the country to 1,265.
It comes after 249 new infections of the COVID-19 variant were reported on Thursday.
The latest figures released by the UK Health Security Agency (UKHSA) show 443 cases have been recorded in England, one in Scotland and four in Wales.
No additional cases have been recorded in Northern Ireland.
A total of 58,194 new COVID infections and 120 deaths within 28 days of a positive test were reported across the UK, the figures showed.
It is the highest daily increase in cases since 9 January this year and the sixth biggest rise on record for the UK.
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A further 24,039 people have received their first vaccine, taking the total to 51,207,496.
Across the UK, 46,674,061 people have now been doubled jabbed after 33,824 got their second dose on Thursday.
Another 469,479 booster or third jabs have been administered, meaning 22,184,983 people have received an extra dose.
Following the release of the daily figures, the UKHSA warned the country will have more than one million Omicron cases by the end of this month, if “current trends continue unchanged”.
However, it added that booster jabs provide 70-75% protection against symptomatic infection.
It comes as further measures to try to control the spread of coronavirus are enforced in England, including a legal requirement for people to wear face masks in a wider range of indoor spaces, including cinemas, theatres, and museums.
Stadiums are also included in regulations published on Thursday evening, but the Department of Health confirmed face coverings will only be mandatory in indoor areas.
Meanwhile, Public Health Scotland has “strongly” urged people to defer Christmas parties in response to the Omicron variant.
Earlier, Scotland’s First Minister Nicola Sturgeon warned of a “potential tsunami of infections” in the face of the fast-spreading strain.
She warned it will “run riot” through the wider population and the R number could rise above 2 – meaning an average of 10 people will the virus will infect more than 20 others.