Britons arriving back from Spain will have to quarantine for 14 days - after the government added it to the list of at-risk countries with just a few hours' notice.
It means people arriving back from Spain, the Canary Islands and Balearic Islands from today - and those who have booked a summer holiday there - face the prospect of two weeks in isolation upon returning.
An announcement was made by the Department for Transport on Saturday evening, with the government asking employers to be "understanding" of workers who need to self-isolate.
It may need to follow its own advice after it emerged that Transport Secretary Grant Shapps is currently in Spain on holiday. He has said he will stay there for the duration of his break then self-isolate as required.
According to The Sunday Times, Mr Shapps had to dial in from Spain at the weekend to discuss altering the guidance with Health Secretary Matt Hancock and Cabinet minister Michael Gove.
The Scottish government lifted its quarantine rules on Spain this week - but says it will now reimpose them.
Northern Ireland and Wales have also followed suit in suspending the so-called "travel corridor".
A UK government spokesperson said: "Following a significant change over the last week in both the level and pace of change in confirmed cases, Spain has been removed from the list of countries where people do not have to self-isolate when arriving into to the UK.
"People currently on holiday in Spain are encouraged to follow the local rules, return home as normal and check the FCO's [The Foreign and Commonwealth Office] travel advice pages on gov.uk for further information."
The spokesperson added: "Protecting public health is our absolute priority and we have taken this decision to limit any potential spread to the UK.
"We've always been clear that we would act immediately to remove a country where necessary."
Britons have been advised against all but essential travel to mainland Spain by the FCO.
Holiday company Tui responded by cancelling all flights to Spain scheduled for Sunday - while British Airways and easyJet said flights would not be immediately affected.
The announcement has caused disappointment among many thousands of holidaymakers.
Chloe Harris, 23, from Kent, booked a last-minute trip to Lanzarote and arrived on the Spanish island on Saturday morning.
She said: "When I heard the news I was quite shocked because I thought they would have given us some warning. Even just some warning that this was something they were going to consider.
"I think a lot of people are going to rush to the airport, but because we are only here for four days, and we only arrived this morning, it doesn't seem worth it."
Labour's shadow home secretary Nick Thomas-Symonds said the news would be "deeply concerning for families" currently in Spain or who were planning a trip, and called for ministers to release details explaining how people affected would be supported.
On Friday, Spain logged 922 infections, slightly down from 971 the day before, but officials are tracking more than 280 active outbreaks across the country.
Spain's government has warned it could already be having a "second wave" of the illness, as France, Germany and Belgium all reported steep rises in their number of cases.
But the foreign ministry released a statement following the UK's decision to reimpose quarantine restrictions, saying: "The Spanish government considers that the situation is under control. Outbreaks are localised, isolated and controlled.
"Spain is a safe country. We respect the decisions of the United Kingdom with whose authorities we are in contact."
Spain joins countries such as the US, Portugal, Sweden, Mexico, Brazil, Russia, Iran, India, Pakistan, Bangladesh and China on England's at-risk list, meaning people returning have to quarantine.
It comes a day after five more countries were added to the list of countries that English holidaymakers could visit without the need to quarantine.
The full list of no-quarantine countries for English holidaymakers is below - while the list of Scottish exemptions can be found here: