Boris Johnson today told cabinet ministers that “early indications” show the omicron variant is more transmissible than delta.
However, the prime minister told his team it was “too early to draw conclusions” on the characteristics of the variant.
His official spokesperson told journalists: “Cabinet started with a discussion on the government’s response to Covid-19 and the omicron variant.
“The prime minister said it was too early to draw conclusions on the characteristics of omicron but that early indications were that it was more transmissible than delta.”
Early data also suggests the variant is milder than the delta variant - which is currently dominant in the UK.
It comes as further measures were introduced this week to help slow transmission.
During the meeting, Johnson also reiterated that booster vaccines remain the “best defence” against new and existing variants.
He said the NHS remained “on course” to meet the target of offering a booster to all adults by the end of January.
Also today, experts warned the omicron variant is spreading through the UK much faster than initially feared.
Tim Spector said early data suggested cases of the covid mutation are doubling every two days, putting it on course to overtake some of the countries where travellers to the UK are required to quarantine.
The professor of genetic epidemiology at King’s College London told BBC Breakfast there was “very little point” in having travel restrictions if case numbers exceeded those in red list countries.
He said: “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 – assume 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.”
Dr Jeffrey Barrett, director of the Covid-19 genomics initiative at the Wellcome Sanger Institute, said he thought omicron would take over from delta in the UK as the dominant variant of coronavirus “within a matter of weeks”.
Health secretary Sajid Javid told MPs on Monday that none of the omicron variant cases identified to date had resulted in hospital admission.
Johnson is expected to give an update on whether any further restrictions are necessary within the next two weeks.
Deputy prime minister Dominic Raab said today the government does not believe its Plan B on Covid-19 is required “because of the success of the vaccine programme”.