LONDON — UK Health Secretary Matt Hancock warned on Sunday that the new mutated strain of COVID-19 currently circulating in parts of England is "out of control" as Prime Minister Boris Johnson announced stricter restrictions ahead of Christmas.

In a press conference, Hancock urged Londoners in the capital, to maintain social distancing, saying, “everybody needs to behave as if they might well have the virus,” as stricter lockdown measures have been imposed.

The virus is not more dangerous but it is highly contagious and rapidly spreading, causing the government to toughen lockdown measures considering this strain poses a greater challenge to authorities over the next two months until the mass vaccination program developed by Pfizer-BioNTech is rolled out, he explained.

Starting Sunday, health authorities vaccinated 350,000 people, mostly elderly over the age of 80, plus health sector employees and workers in nursing homes, Hancock revealed.

Hancock added the government acted "very quickly and decisively".

Also European countries banned flights from the UK on Sunday and the WHO called for stronger containment measures as the British government warned that a potent new strain of the virus was "out of control".

As the World Health Organization urged its European members to strengthen measures against a new variant of COVID-19 circulating in Britain, the Netherlands imposed a ban on UK flights from 6:00 a.m. (0500 GMT) on Sunday and Belgium said it would follow suit from midnight with ban on planes and trains from the UK.

Alarm bells were ringing across Europe — which last week became the first region in the world to pass 500,000 deaths from COVID-19 since the pandemic broke out a year ago — after it appeared that a new, even more infectious strain of the virus was raging in parts of Britain.

Germany, too, was considering a similar move as "a serious option" for flights from both Britain and South Africa, where another variant was discovered, according to a government source.

Italy will join the ban in order to protect its citizens, Foreign Minister Luigi Di Maio wrote on Facebook, without specifying when the measures would come into force. Austria's Health Ministry told the APA news agency that it would also impose a flight ban, the details of which were still being worked out.

Meanwhile, the UK prime minister said on Saturday that London and parts of southeast and east England will move to "Tier 4" restrictions with all non-essential shops closing from Sunday.

People in those areas must stay at home and cannot travel during the holidays and the government is recommending that people in all Tiers should stay local and not travel during Christmas.

"It is with a very heavy heart I must tell you we cannot continue with Christmas as planned," Johnson said at a press conference on Saturday, stating that they "bitterly regret" the changes that need to be made.

The government had originally planned to relax rules allowing three households to meet over five days for Christmas, but that will now be limited to just Christmas Day.

It comes after a really "dramatic increase" in infections in the southeast and London where in some areas, most of the new COVID-19 cases are the new variant, said Professor Chris Whitty, England's chief medical officer.

Whitty said that in other parts of England, this new variant was less present but that due to its transmissibility they were encouraging people not to travel.

"The new variant contains 23 different changes," said Sir Patrick Vallance, the UK's chief scientific officer, who described them as a "constellation of changes".

Officials announced that the new strain was much more contagious due to these changes and up to 70% more transmissible. "We think it may be in other countries as well," added Vallance.

Wales First Minister Mark Drakeford said his nation would also lockdown from Sunday following a meeting with UK officials over the new variant.

In Wales, people from two households can gather in a "bubble", Drakeford said. "The situation is incredibly serious. I cannot overstate this," he said.

Scottish First Minister Nicola Sturgeon said that some cases of the new variant were also in Scotland and the household mixing would be limited to Christmas Day.

Scotland will apply level four measures from Dec. 26 for three weeks, closing non-essential shops and restaurants. — Agencies