A further 86 cases of the Omicron Covid variant have been reported in the UK, taking the total to 246, health authorities confirmed on Sunday.
This compares with a total of 160 on Saturday, an increase of more than 50 per cent, Xinhua news agency reported, citing the UK Health Security Agency's (UKHSA) figures.
Meanwhile, the UK has registered 43,992 new Covid-19 infections, bringing the total number of coronavirus cases in the country to 10,464,389, according to official figures.
COVID in UK
The country also reported a further 54 coronavirus-related deaths. The total number of coronavirus-related deaths in the UK now stands at 145,605. These figures only include the deaths of people who died within 28 days of their first positive test.
The latest data came as British Health Secretary Sajid Javid said all international arrivals to the country, including children over the age of 12, will need to take a pre-departure test from 0400 GMT on Tuesday. He added that they must be taken a maximum of 48 hours before departure.
In addition, from Monday, Nigeria will be on the red travel list. It joins several southern African nations which were put on it after the Omicron variant was first detected late last month.
"I think it's too late to make a material difference to the course of the Omicron wave if we're going to have one," professor Mark Woolhouse, a member of the Scientific Pandemic Influenza Group on Modelling (Spi-M), told the BBC, when asked about the new travel rules.
More than 88 per cent of people aged 12 and over in the UK have had their first dose of vaccine and nearly 81 per cent have received both doses, according to the latest figures.
More than 35 per cent have received booster jabs, or the third dose of a coronavirus vaccine.