Omicron cases have hit 437 as 101 new infections have been confirmed.
It is an increase from yesterday when 90 new cases of the new Covid variant were recorded.
This includes a further 72 cases in England, 28 in Scotland and one in Wales, according to figures from the UK Health Security Agency.
The worrying increase comes as the UK could face more Omicron cases than some red countries.
New rules designed to slow the spread of the Omicron variant of coronavirus will see travellers having to take a pre-departure test before travelling to England from Tuesday.
All travellers will be required to take a Covid-19 pre-departure test, amid warnings that the time between infection and infectiousness could be shorter with the new strain.
Professor Tim Spector, from the Covid Zoe app, said that in around 10 days' time the UK could have more cases of Omicron than some countries it had put on the travel red list.
The professor of genetic epidemiology at King's College London told BBC Breakfast: "The official estimates are about 350-odd Omicron cases, and because the current testing is missing a lot of those, it's probably at least 1,000 to 2,000 I would guess at the moment.
"And we are expecting this to be doubling about every two days at the moment, so if you do your maths - say assumed it's 1,000 at the moment, and you think it's going to be doubling every two days, you can see that those numbers are going to be pretty (high) certainly in about 10 days time.
"By that time, we'll probably have more cases than they will in some of those African countries.
"So I think these travel restrictions do perhaps have their place initially, when cases are really low here and really high in the other country, but when we reach that equilibrium, there's very little point in having them in my opinion."
Cases of the new Omicron covid variant are increasing across the UK after it was initially detected in southern Africa.
The strain was first located in the UK in Chelmsford and Nottingham on November 27, 2021. Since then, cases have been rapidly increasing across the country.
Today, the UK has reported the highest number of weekly Covid cases since the lockdown in January.
A total of 336,893 new cases were recorded in the past seven days, including the 46,691 new infections reported today, according to government figures.
It marks the highest number over a seven-day period since the week to January 16 when 339,956 infections were reported.
Yesterday, 459 new Covid cases were recorded across the UK today marked a 9.1 per cent increase on the seven-day average, with 330,918 new cases recorded over the past week.
Despite this, the number of deaths recorded yesterday was 41, a decrease of 0.2 per cent on the seven-day average.
Daily confirmed Covid cases have been rising again since early November, though the UK’s successful vaccination programme appears to have largely broken the link between infections and deaths.
A sustained increase in cases comes as concerns grow about the Omicron variant, with an expert today saying there are likely to be more than 1,000 cases of Omicron in the UK, just 10 days after the coronavirus was first discovered.
