Britain "will temporarily close all travel corridors from 0400 on Monday", to "protect against the risk of as yet unidentified new strains", the prime minister said at a virtual press conference at Downing Street.
They will also have to show proof of having tested negative for coronavirus in the 72 hours before their trip if they arrive by plane.
Pressed over why the border controls were only being introduced now, Mr Johnson said: "What we're doing now is taking steps that you'd expect to protect against the new variants because the situation now is we have a very high rate of domestic infection in the United Kingdom combined with a massive vaccination programme".
Transport Secretary Grant Shapps tweeted that the stricter rules are because it is "impossible" for the government's Joint Biosecurity Centre to "provide live scientific updates to predict which countries or regions will now originate new variants".
He said that his government was stepping up the enforcement of travel quarantine rules at the border and in the country.
Mr Johnson added: "At this crucial stage what we can't have is new variants with unknown qualities coming in from overseas and that's why we've set up the system to stop arrivals from places where there are new variants of concern and set up the extra tough measures that I've outlined".
He said the country is involved in one of the fastest vaccination programmes in its history, but added: "It will be fatal if this sense of progress were now to breed any kind of complacency because the pressures on the NHS are extraordinary".
Vijay-starrer Master to get a Hindi remake
The Lokesh Kanagaraj-directorial released on Thursday in Tamil and its Hindi dubbed version hit screens on Friday. Flying starts at key worldwide markets. "A strong start, despite limited screens.#MasterFilm #MasterPongal".
"This is not the time for the slightest relaxation of our national resolve and our individual efforts, so please stay at home", he said.
Officials believe the declining case rates are due to the stringent rules, but concede there will be a time lag before hospitalisations and deaths may also drop.
The measures apply to all travelers, including British and Irish nationals.
England is now under the third national lockdown since the outbreak of the pandemic in the country.
The government imposed partial lockdowns on England in November as the government raced to curb spiking infections, while there were also restrictions in Wales, Scotland, and Northern Ireland.
Two variants of interest have been identified in Brazil - though only one, which has a small number of mutations, has been detected in the UK.
According to BBC, the new policy, which comes into effect from 4 am on Monday, means that arrivals from every destination will need to self-isolate for ten days, or receive a negative result from a coronavirus test taken at least five days after they enter the UK. In Britain, 3,325,636 cases of coronavirus and 87,448 fatalities have been reported so far.
Former Nets guard Caris LeVert is out indefinitely after the James Harden deal led to a scary finding in his physical. He becomes the first National Basketball Association player to do so right in his very first game with a new team.
He is expected to be out of town well before Biden is sworn in on the steps of the Capitol building at exactly noon. Baker is described as anti-Trump, anti-government, anti-white supremacists and anti-police.
Until the request lapses on March 30, the FAA will supposedly not issue cautioning letters or arrange punishments. American is also moving crew members out of downtown hotels for their layovers in the D.C. area.
Auparavant, l'Agence nationale de gestion des catastrophes (BNPB) avait fait état de sept morts et de plus de 200 blessés. Pour éviter la propagation du Covid-19, les autorités ont séparé les groupes à haut risque et à risque plus faible.
Several hundred law enforcement officers and National Guard troops milled around Georgia's state house in Atlanta early Sunday. Capitals in battleground states, where Trump has directed his accusations of voter fraud, were on especially high alert.
Davis announced Thursday he has "entered into an agreement" to buy the Las Vegas Aces from MGM Resorts International . Davis relocated the Raiders from Oakland to Las Vegas ahead of the new season, having spent 25 years in California.
Il faisait là référence au nombre des décès dus au Covid-19 annoncé la veille par l'Institut Johns Hopkins aux Etats-Unis. Ali Khamenei a également ajouté que l'Iran pourrait obtenir des vaccins "auprès d'autres pays fiables".
Il s'est d'abord dit que Brigitte Macron pourrait participer à "Mask Singer ", déguisée en grosse tirelire cochon. Brigitte Macron prend très à cœur son rôle de présidente de la Fondation Hôpitaux de Paris-Hôpitaux de France.
American investigators are now examining if the incursion originated where Russian intelligence operatives are deeply rooted. Given Microsoft's dominance in the IT space, such a compromise could be devastating to many more organizations.
The club are now in 19th position in the Championship , at risk of relegation to League One if their form does not improve. After an impressive showing for England at Euro 2004 he was signed by United in a 27 million pound ($37 million) transfer.
The Israeli government signed a deal with Pfizer and BioNTech in November for 8 million doses of their COVID-19 vaccine. At the same time, just under three-quarters say mask wearing should be compulsory.
United Kingdom to host G7 summit face to face in June
Britain has invited Australia, India, and South Korea with the aim of using the occasion to boost cooperation among democracies. The three countries have been invited to the summit as guests to "deepen the expertise and experience around the table".
Trump unblocked on Facebook, Instagram
Trump and the accounts of his campaign and some top advisers were also suspended from Instagram , Snapchat, Spotify, Shopify, Pinterest, and several other platforms.
William urges public to follow queen's example and get jab
Prince William has said he is "very proud" of the Queen and the Duke of Edinburgh for getting their coronavirus vaccinations. His comments came during a video call with medics who told him there is " vaccine hesitancy" in some groups.