Travellers from Portugal arriving in Scotland must now spend a fortnight in isolation.
The rules came into force from 4am on Saturday, 24 hours after Wales introduced the same quarantine period for those arriving from the country.
However, they do not apply to England and Northern Ireland – leading to confusion and frustration among holidaymakers.
Shapps: ‘I understand there’s confusion’
Portugal had only been removed from the UK quarantine list two weeks ago but coronavirus cases have now risen back above 20 cases per 100,000 people – the threshold used for past travel decisions.
Meanwhile, travellers from Greece to Scotland were told to isolate from Thursday.
Wales did the same for six Greek islands, including Crete and Zante, but England and Northern Ireland resisted.
Britons abroad confused over quarantine rules
Despite the differences, Prime Minister Boris Johnson insisted that “overwhelmingly the UK is proceeding as one”.
But earlier on Friday Transport Secretary Grant Shapps said there was now “confusion” over differing quarantine rules across the union and accused Scotland of having “jumped the gun” on imposing restrictions on Greece.
A Scottish government spokesman hit back saying there had been a “worrying number of people in Scotland who tested positive for COVID-19 and who had returned from Greece”.
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The spokesman added: “In the case of Portugal, it was unfortunate that the UK government announced their decision [not to impose quarantine on travellers] yesterday before ministers from England, Scotland and Northern Ireland met and before considering the latest Joint Biosecurity Centre (JBC) data.
“This indicated a significant rise in both the prevalence of the virus in Portugal and in test positivity.”
Welsh health minister Vaughan Gething said Wales was acting “in line with” the risk assessments from the JBC in imposing a 14-day quarantine on arrivals from the six Greek islands and Portugal.
‘It’s very unfair’: Tourist on Portugal confusion
Holidaymakers in Portugal reacted with confusion when the rules were announced, with many already having booked earlier flights home.
One tourist, a man called Derek visiting the town of Almancil, told Sky News that his son and wife did not join him because they feared quarantine being imposed and his brother had rushed home to go back to work and help his son head to university.
He claimed holidaymakers were being left “confused” and that “it’s very unfair because people seem to be put on short notice; not only is it very expensive but they don’t know if they’re coming or going”.
