Boris Johnson announced at Friday's coronavirus press briefing that the UK would be closing “all travel corridors” from 4.00am (GMT) on Monday.
People wishing to fly to the country after this time must provide proof of a negative Covid test before taking off.
They will also need to quarantine for 10 days in line with current government guidance, unless they test negative after five days.
The prime minister is hoping that the blanket suspension of all travel corridors will bolster Thursday's ban on flights arriving from Portugal and South America and keep the new Covid variants at bay.
He described the extra measures as "vital" in stopping "these strains from entering the country" and derailing the vaccination programme, which has so far seen 3.2 million people across the country receive their first dose.
One of the two Brazilian strains of coronavirus was recently detected in the UK.
On Saturday, British airports called for urgent government support warning the sector was heading for a "very difficult" place.
Karen Dee, chief executive of Britain's Airport Operators Association, said the government needed to go beyond existing support that includes a temporary exemption from local property taxes.
“The UK and devolved governments (for Scotland, Wales and Northern Ireland) now need to set out as a matter of extreme urgency how they will support airports through this deepening crisis," she said.
Tim Alderslade, chief executive of industry body Airlines UK, said the first three months of the year were typically a slow period for the sector, but called for plans to relax rules during the peak spring and summer period.
"Easter is a date that we have got in mind for when we can start to have an aviation sector again. If we don’t start bringing revenue into the sector, we’re going to be in a very difficult place indeed," he told BBC radio.
"Airlines have been staying in business by taking on billions of pounds of debt which will need to be paid back," he added.
The UK registered 55,761 positive cases on Friday as well as 1,280 deaths, marking five successive days of the daily toll exceeding the thousand mark.
Chief Medical Officer Chris Whitty offered a crumb of comfort, saying that while the infection rate in the country was “just shy of one in 50 people”, there was now a “levelling off” of cases.
Mr Johnson has stoutly defended the vaccine distribution programme which has come under criticism for a lack of supplies and regional disparities in administration.
"Yesterday alone, we vaccinated around a quarter of a million people in England, and that is still far more than any other country in Europe," he said.
A speedy and successful distribution of vaccines has become the UK's only hope to alleviate a pandemic which in recent days has spun out of control.
It comes as the EU said it was looking at a common vaccine certificate to help get travellers go on holiday and prevent tourism from suffering another disastrous year.
European Commission President Ursula von der Leyen said the certificates for individuals who have been vaccinated could be combined with Covid-19 tests for those awaiting shots to allow as many people as possible to travel during the summer, which is vital for warm weather Mediterranean destinations like Greece, Italy and Spain.
The issue will likely be discussed during a video meeting of EU leaders next week. Europeans have been concerned residents might be split into two camps - those with vaccine certificates permitting them to travel and others who remain limited in where they can go.
But von der Leyen said such discrimination is unnecessary because “you can always combine either a certificate or a negative Covid test, if you did not have access to a vaccination so far.”
“So there are possibilities to find a fair and equal balance,” she said during a visit to Portugal’s capital, Lisbon, on Friday.