India will be added to the UK's Covid travel 'red list' forcing arrivals into hotel quarantine from 4am this Friday.
The major decision on the country of 1.4billion people was announced today by Health Secretary Matt Hancock after a surge in cases - and fears over a new Indian variant.
He admitted 103 cases of the B1.617 mutant strain have now been detected in the UK - up from 77 last week - and a small minority do not have links to international travel.
There will be surge testing to "limit the spread as much as possible", Mr Hancock said, but did not give further details.
Mr Hancock also revealed UK authorities have now detected 557 cases of the separate South African Covid variant since it was first identified in December - and one-third of them had no immediate link to international travel.
Many have been in a cluster in South London in Wandsworth, Lambeth and Southwark, along with single cases in the last week in Barnet, Birmingham, and Sandwell.
There has been “a small amount of community transmission” of the South African variant, which may respond less well to the vaccine, Mr Hancock admitted.
The Prime Minister cancelled his own trip to Delhi today after the region imposed a six-day lockdown from 10pm tonight.
But the PM and Mr Hancock had faced questions over why India had still not been put on the red list for travel - despite demands by Labour to do so last week.
Daily COVID-19 cases in India jumped a record 273,810 on Monday and deaths rose a record 1,619 to 178,769.
Fewer than 100 critical care beds were available yesterday in the city of New Delhi, with a population of more than 20 million people.
Currently people can still arrive from India and quarantine only in their own homes.
By comparison, travel to the UK from 39 red list countries - to be 40 once India is added - is banned except for UK residents, who must stay in a £1,750 quarantine hotel for 10 days.
Concerns have been rising about the B1.617 mutant strain spreading through India.
Mr Hancock said tests are still ongoing on whether it should be branded a 'variant of concern'. It's not yet known if it transmits more easily than 'normal' Covid or is resistant to a vaccine - but India has now been added to the red list anyway as a "precaution".
SAGE advisor Prof Andrew Hayward earlier suggested the government would have to act "sooner rather than later" over the B1.617 mutant strain.
Mike Tildesley, a member of SAGE sub-group the Scientific Pandemic Influenza Group on Modelling (Spi-M), said as much information about the new variant must be gathered "as quickly as possible".
Dr Jeffrey Barrett, director of the Covid-19 Genomics Initiative at the Wellcome Sanger Institute, said the variant should be "watched carefully" but it was not the most worrying.
He told the BBC: "This variant has a couple of mutations that are among those that we think are important that should be watched carefully.
"But they're actually probably not at the very kind of top tier of mutations, for example in the B117 - or Kent variant - or the South African variant, that generate the most concern.
"And in terms of spread, clearly this variant has increased in frequency in India around the same time as their very large and tragic recent wave,
"But I just don't think we know yet whether there's a cause and effect relationship - is this variant driving that spread? Or is it happening at the same time perhaps due to a coincidence?"
Mr Hancock spoke after government figures confirmed more than 10 million people in the UK have received two doses of a coronavirus vaccine.
Almost one in five adults in the UK (19%) have now received two jabs.
And a real-world study by Public Health England suggests the vaccines saved more than 10,000 lives between December and March, on top of reducing hospitalisations.
Boris Johnson hailed the “fantastic” news adding: “This is another remarkable milestone in our vaccination programme, which has already saved thousands of lives.
“I want to thank the brilliant staff and volunteers involved in the rollout, and urge all those who are called to keep coming forward.”
Mr Hancock hailed the 10million second doses, saying uptake of the jab is 94% among over-50s as a whole.
Mr Hancock told MPs: “Three quarters of over 75s have now had both jabs, rising to four fifths of over-80s.
“The vaccine is our way out of this pandemic and I’m delighted it’s being taken up in such huge numbers.”
But he said take-up was still below 80% among care home staff in more than half of council areas. A consultation is under way on making the vaccine mandatory for most care home staff and “we’ll consider all options”, Mr Hancock said.
Meanwhile the Health Secretary said the Government is "ramping up" plans for a booster shot this winter to ensure the Covid-19 vaccines "stay ahead of the virus".
He told MPs: "We've already procured enough vaccine doses to begin the booster shots later this year.
"We will be working with our current vaccine suppliers and new suppliers, like the CureVac partnership, to work out which vaccines will be effective as a booster shot and to design new vaccines specifically targeted at the variants of concern - like the variant first found in South Africa.
"Our goal is to ensure the vaccine protects against this dreadful disease, whatever it throws at us, to keep us safe and to protect our much-cherished return to normal way of life."