Travel industry leaders have reacted with fury to the decision to put six southern African countries on the red list.
The UK government was accused of a “knee-jerk” reaction to fears over a new variant of coronavirus.
South Africa, Botswana, Lesotho, Eswatini, Zimbabwe and Namibia were put on the UK’s red list at noon on Friday.
Passengers arriving from those countries after 4am on Sunday will be required to spend 10 days in a quarantine hotel at a cost of £2,285 (€2,698.82).
Those arriving before then will need to self-isolate at home for 10 days and take additional coronavirus tests.
Direct flights from the six countries are banned until the hotel quarantine scheme resumes, leading to cancellations by airlines including British Airways and Virgin Atlantic.
The measures were announced by UK health secretary Sajid Javid on social media shortly before 9pm on Thursday.
Travel consultancy The PC Agency estimated that between 10,000 and 15,000 British citizens are in South Africa on temporary visits.
The firm’s chief executive Paul Charles accused ministers of making “another knee-jerk decision”.
He told the PA news agency: “While government has to act swiftly on any serious threats, it should be steering away from imposing blanket country measures such as flight bans.
“It would be better to assess travellers based on their individual risk, and ask fully jabbed consumers to test regularly at home rather than force them to pay over £2,000 per person to stay in grim hotel quarantine.
“Variants will come and go for years yet so the government has to find new, less economically damaging measures to deal with each situation.
“Yet again, we are now in a position where government is knocking consumer confidence with such draconian measures.”
Travel data firm Cirium said 289 UK flights were scheduled to and from South Africa in December, with capacity for 79,000 passengers.
Julia Lo Bue-Said, chief executive of Advantage Travel Partnership, the UK’s largest independent travel agent group, said: “Yet again, an entire industry is informed of drastic changes to travel restrictions by a late-night tweet from government, leaving travel agents scrambling to repatriate their customers in these southern African countries and cancel and rebook those who had planned to travel over the festive period.
“It’s important to remember that many of these people who are overseas in these destinations would be visiting friends and family for the first time in over two years – and now they have to make the heart-breaking decision to return home early.
“Not only that, but there is only a very small window for passengers to try and make it home in time to avoid the inhumane hotel quarantine and a hefty bill to go with it.
“Why can’t this be replaced with home self-isolation and appropriate testing instead?”
Ms Bue-Said said the wider knock-on effect for consumer confidence is “deeply concerning for the travel industry”.
She added: “We simply cannot operate our businesses with this level of uncertainty hanging over us for the foreseeable future.”
A spokeswoman for travel trade organisation Abta said the announcement was “devastating” for travel companies that specialise in travel to Southern Africa.
She went on: “These businesses have had very little opportunity to generate income for almost two years and now face a further period of being unable to trade – just as the region’s peak season begins.
“The government must consider stepping in to provide targeted support where precautionary measures such as these close UK travel businesses, as they have done previously for other sectors of the economy.
“It is also vital the decision is kept under careful review and that restrictions are lifted promptly if it becomes clear there is not a risk to the UK vaccination programme.”
