Ibiza, Mallorca and Menorca are at risk of going back on the amber travel list, just two weeks after they were moved to the green watchlist.
The Balearic Islands are among the most popular holiday destinations where Brits can currently travel to without having to quarantine on the way back.
But after a surge in cases on the islands, there are fears they could be moved back to the amber list, meaning British travellers will have to self-isolate for 10 days on their return to the UK.
At the moment, the islands are reporting 258 cases per 100,000 people, according to Cercle d’Economia de Mallorca.
When Grant Shapps made his latest travel announcement two weeks ago, he warned that any country on the green watchlist could be moved to the amber list if the number of cases increases.
Countries on the watchlist will be kept under review, with the government monitoring the pandemic and acting swiftly, especially if any new variants of concern emerge.
Ministers said in a statement: “The Government will not hesitate to act immediately should the data show that countries risk ratings have changed.”
In the same way, countries on the amber list could be moved to the red list if there is a surge in infections.
People arriving in the UK from a red-list location must spent 11 nights at a quarantine hotel, at a cost of £1,750 for solo travellers.
A final decision on the latest update to the traffic light system is set to be approved by ministers tomorrow and the travel lists are expected to be updated on Thursday.
Under new rules coming in the next week, however, fully vaccinated Brits will not be required to self-isolate when returning from an amber list country.
If the Balearic Islands are moved to the amber list, young people who have only had one jab or who still need to get their first vaccine will need to quarantine when they return home after their holiday.
It would also be a blow for the travel industry as bookings surged after the popular destinations were moved to the green list.
A source told The Sun : “It’s all still up for discussion, but the figures aren’t great which is why it was on the watch list in the first place.”
Italy, Germany and Poland are among the destinations most likely to be added to the Government’s green travel list, according to an analyst.
Robert Boyle, former director of strategy at British Airways’ parent company IAG, predicted that 12 countries could be put in the low-risk tier this week.
He said this includes nine European countries which are all “strong candidates”, consisting of Austria, Bulgaria, Germany, Italy, Latvia, Lithuania, Poland, Slovakia and Switzerland.