Thousands of British holidaymakers have been given until the early hours of Saturday morning to return from Croatia to avoid new quarantine measures.
But Britons can go to Portugal, for the first time in weeks, without having to isolate when they return.
The transport secretary, Grant Shapps, announced that travellers arriving from Croatia, Austria or Trinidad and Tobago, after 4am on Saturday will have to quarantine for 14 days.
They are the latest countries to be added to the list, joining other major holiday destinations including France and Spain.
Increasing rates of the coronavirus in parts of Europe have played havoc with the travel plans of millions.
At the same time, Mr Shapps said the latest data showed that the government could now add Portugal to those countries included in so-called ‘travel corridors’.
Writing on Twitter, however, he warned: “As with all air-bridge countries, please be aware that things can change quickly.
“Only travel if you are content to unexpectedly 14-day quarantine if required (I speak from experience!).”
The cabinet minister spent two weeks in quarantine after Spain was removed from the safe list of countries in July just hours after he jetted into the country for a family break.
The decision to add the new countries to the quarantine list was based on a “significant change in both the level and pace of confirmed cases”.
The weekly incidence per 100,000 people for Croatia has increased from 10.4 on 12 August to 27.4 on 19 August – a 164 per cent increase.
In Trinidad and Tobago, cases have seen a marked increase over the past month, with a 232 per cent rise in the number of cases per 100,000 people between August 12 and 19.
In Austria, the weekly number of cases per 100,000 of the population increased from 10.5 on 13 August to 20.3 on 20 August, a 93 per cent increase.