British foreign minister Dominic Raab on Sunday stood by his government's abrupt decision to impose a two-week coronavirus quarantine on travellers returning from Spain, which has provoked anger and confusion among tourists.
The move to take Spain off a safe-travel list was announced late on Saturday and took effect from midnight (2300 GMT on Saturday), leaving travellers with no time to dodge it or plan ahead.
Raab defended the imposition of the quarantine as a "real-time response" to a jump in Spanish coronavirus cases reported on Friday, the latest in a month-long resurgence in infections.
"We can't make apologies...we must be able to take swift, decisive action," he said on Sky News.
The opposition Labour Party's health policy chief, Jonathan Ashworth, slammed Prime Minister Boris Johnson's government for its "frankly shambolic" handling of the measure, which has scuppered the plans of many would-be holidaymakers.
The move will also hit hard at the Spanish tourism sector just as it is starting to recover from months of coronavirus lockdowns and travel restrictions.
At Madrid's Barajas airport Emily Harrison, who was taking a flight to London and faced the prospect of having to self-isolate for two weeks.
"It's really bad because it's just come all of a sudden, it's not given very much time to prepare so everyone is now panicking," said Harrison, from Essex.
"We had a wedding to go to and we had plans to visit friends and family who we haven't seen in a very long time and now we are going to have to cancel all those plans, so it's really quite upsetting."
Spain had been on a list of countries that the British government had said were safe for travellers to visit - meaning tourists returning home would not have to go into quarantine.
But it has seen cases rise in the last few weeks, prompting most regions to impose rules for masks to be worn everywhere and, in several areas including Barcelona, calls for people to stay at home.
"We're quite frustrated by it to be honest, because it actually feels safer in Spain," British tourist Carolyne Lansell, said of the quarantine decision. She was flying to Ibiza from Madrid for a 10-day holiday before going home.
A Spanish Foreign Ministry spokeswoman said on Saturday evening that Spain "respects decisions of the United Kingdom" and was in touch with the authorities there.
Spain was one of the worst hit countries in Europe by the pandemic, with more than 290,000 cases and over 28,000 deaths. It imposed very strict lockdown measures to contain the spread, gradually easing them earlier in the summer.
The British decision follows steps by Norway on Friday to re-impose a 10-day quarantine requirement for people arriving from Spain, while France advised people not to travel to Spain's northeastern region of Catalonia.
But a collapse of tourism from Britain would have far more of an impact on the economy in Spain, where tourism accounts for 12% of GDP. Britons made up more than 20% of foreign visitors to Spain last year, the largest group by nationality.
"This decision is an absolute disaster for the recovery, there's no other way to see this," Angel Tavares, head of European Economics at Oxford Economics consulting, said on Twitter, referring to the quarantine ruling.
Antonio Perez, the mayor of Benidorm, a Mediterranean resort that is hugely dependent on British tourists, said it was a "tough blow".
In addition to the quarantine, the British foreign ministry advised against all but essential travel to mainland Spain.
Regional authorities in the Canary and Balearic Islands, which are popular holiday destinations, said they would try to get an exemption from the quarantine for people travelling back from the archipelagos.