Another 101 Omicron COVID variant cases have been recorded in the UK, taking the total across the country to 437.
This compares with 90 new cases reported on Monday.
The latest daily data from the UK Health Security Agency shows 72 cases were in England, 28 in Scotland, and one in Wales.
So far, no confirmed Omicron cases have been recorded in Northern Ireland.
It comes as the UK reported a total of 45,691 new COVID cases in the latest 24-hour period.
A further 180 people have died within 28 days of testing positive for coronavirus.
Currently, 7,317 COVID patients are in hospital in the UK, including 901 in ventilation beds.
According to the latest government data, 19,979 more people have had a first vaccine dose in the last 24 hours, another 25,012 have received a second jab, while a further 329,165 have had a booster or third dose.
Omicron ‘more transmissible’
Earlier on Tuesday, Prime Minister Boris Johnson said early indications suggest Omicron is more transmissible than the Delta variant.
He made the comment as he updated ministers on the COVID situation at a cabinet meeting.
Giving an account of the meeting, the PM’s spokesman said: “The prime minister said it was too early to draw conclusions on the characteristics of Omicron but early indications were that it is more transmissible than Delta.”
Downing Street also warned that it is still unclear what impact the vaccines have on the new variant.
The warning comes after Health Secretary Sajid Javid told MPs that Omicron cases have been identified in people without any travel history – meaning it is now being contracted within the community.
‘There could be 1,000 Omicron cases a day in UK’
On Monday, a leading scientist told Sky News that the Omicron variant is already causing up to 1,000 infections a day in the UK.
Professor Francois Balloux, director of the University College London Genetics Institute, said the outbreak was now well under way, doubling every three to four days.
Meanwhile, British drugmaker GSK has announced that its antibody-based COVID-19 therapy with US partner Vir Biotechnology is effective against all mutations of the Omicron variant.
The unpublished data shows that the companies’ treatment, sotrovimab, is effective against all 37 identified mutations to date in the spike protein, GSK said in a statement.
Another pre-clinical data showed that the drug had worked against key mutations of the Omicron strain.
Last week, it was approved for UK use by the Medicines and Healthcare products Regulatory Agency (MHRA).
Also on Tuesday, pre-departure COVID testing for people arriving in the UK was reintroduced, with travellers also required on arrival to take a day two PCR test and isolate until they receive a negative result.