Tough new Covid controls could be in place for months, Health Secretary Matt Hancock has warned as he admitted a mutant new strain of the virus was running "out of control".
Countries across Europe began banning flights from Britain after the disclosure the country is the centre of the outbreak of the new variant, which is up to 70% more transmissible than the original.
Concerns about the rapid spread of the disease were underlined with the publication of the latest official figures showing there had been a further 35,928 lab-confirmed cases of coronavirus in the UK as of 9am on Sunday.
Dr Yvonne Doyle, medical director at Public Health England, said: "This sharp and sudden increase is of serious concern."
She said most of the new cases were concentrated in London and the South East – where the new strain is thought to have originated – although it was too soon to say if they were linked to it.
Meanwhile, Ireland and France have become the latest countries to ban travel from Britain with the measures set to come force at midnight and last for at least 48 hours.
Earlier the Netherlands said it was stopping flights from the UK at least until the end of the year while Belgium has imposed a 24-hour ban on flights and rail links while it assesses the situation.
Italy is prohibiting entry to the country by anyone who had been in the UK in the last 14 days while flights are banned until January 6.
Austria and the Czech Republic are also imposing new restrictions, with Prague announcing stricter quarantine rules with anyone arriving in the country having spent at least 24 hours in UK territory required to self-isolate.
The moves come after Boris Johnson effectively cancelled Christmas for millions of families in London and the South East with a two-week lockdown over the festive period, with people limited to mixing with one other person from another household outdoors.
Families in the rest of England were told households could mix for one day only – on Christmas day – a move mirrored by the devolved administrations in Scotland and Wales.
Wales has also begun another two-week lockdown while Scotland is to maintain a travel ban with other parts of the UK over the holiday period.
Mr Hancock acknowledged that the speed of the changes had left people feeling "cross, frustrated and in many cases angry".
He said the country was facing an "enormous challenge" after scientists warned the new VUI 202012/01 variant could be up to 70% more transmissible than the original virus.
"The new variant is out of control and we need to bring it under control," he told BBC1's The Andrew Marr Show.
"We don't know how long these measures are going to be in place. It may be for some time until we can get the vaccine going."
He said that restrictions on people travelling in and out of the new Tier 4 area of London and the South East were intended to prevent the spread of the new variant to other parts of the UK.
However Welsh health minister Vaughan Gething said it was already present in Wales and was a factor in the rapid rise of cases there.
"The undoubtable truth is this new variant is effectively seeded across the country, so acting now takes account of the fact that this new variant is undoubtedly a factor – we can't say how much of a factor – in the rapid growth in cases across south Wales," he told the BBC.
Mr Hancock insisted they had acted "very quickly and decisively" after ministers were told on Friday by scientists on the Government's New and Emerging Respiratory Virus Threats Advisory Group (Nervtag) that the new strain was spreading more quickly.
However, Labour leader Sir Keir Starmer said the alarm bells had been "ringing for weeks" and called on Mr Johnson to apologise to the country for failing to act sooner.
"It is an act of gross negligence by a Prime Minister who, once again, has been caught behind the curve," he told an online press conference.
"At the heart of the problem here is a Prime Minister who simply doesn't want to be unpopular and therefore won't take the tough decisions that are necessary until he is forced into them at the 11th hour."
The regulations creating a new Tier 4 in England came into force at 7am on Sunday and will be laid before Parliament, which is in recess, on Monday.
The statutory instrument was made at 6am on Sunday, and must be approved by both the House of Commons and House of Lords within 28 days, otherwise the change to the law is reversed as per a process known as the "made affirmative procedure".
The announcements prompted a rush to the London train stations with footage posted on social media showing large crowds at St Pancras waiting to board trains to Leeds.
Mr Hancock said such behaviour was "totally irresponsible" while Transport Secretary Grant Shapps said additional police were being deployed to ensure that only people who needed to travel did so.