The transport secretary has defended reintroducing coronavirus quarantine restrictions for Spain, as he arrived back in the UK to begin his 14 days in isolation.
Grant Shapps said failing to act over growing numbers of COVID-19 cases in the country would have been a "dereliction of duty".
"We had to act when we did," he said, after cutting short his own trip to Spain.
"The figures since have shown why that was required and I'm desperately sad and sorry for people who have lost their holidays.
"I decided I needed to come home early and begin my 14 days quarantine just to make sure that I can get on with my job."
Mr Shapps also revealed that ministers had looked at excluding the Balearic and Canary Islands from the coronavirus quarantine.
But he added: "Chris Whitty, the chief medical officer, was very clear with us that he was concerned about the data, we had seen how the data had come very fast forward in Spain in 20, 48 hours, it had gone up by 75%.
"It had doubled in just a few days. He was concerned to see what was happening in the islands, and that's why we make it a whole-country approach in these things."
The transport secretary flew to Spain on Saturday morning to start his summer holiday, just hours before the government announced it was scrapping its travel corridor for the whole of the country.
It means that Britons returning to the UK from Spain now have to self-isolate for 14 days when they get back.
Mr Shapps said he "cannot rule out" other countries joining Spain on the quarantine list.
The decision has angered tourists, airlines and travel firms.
The Foreign and Commonwealth Office updated its travel advice for Spain on Monday.
It is now advising against all non-essential travel to the whole of Spain, including the Balearic and Canary Islands.
Jose Ramon Bauza, a former president of the Balearic Islands, said he "doesn't understand" the decision.
"Of course we had some vacuums of coronavirus in Spain, but most of the regions are absolutely low numbers - including better than Britain," he told Sky News.
"I can assure you that being here in the Balearics is absolutely safe - it's as safe as any other place in Europe."
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A minister told Sky News earlier that the government is poised to put more countries on its quarantine list "straight away" if coronavirus runs "out of control" in them.
Belgium, Luxembourg and Croatia are being looked at by ministers given the rates of coronavirus there, the Daily Telegraph reports.
Culture Secretary Oliver Dowden would not say which countries could be next on the quarantine list, but confirmed those where the virus is "rising rapidly" and there is a risk of Britons "coming back in numbers" are of most concern.
Heathrow Airport has proposed a regime of testing in a bid to reduce 14-day quarantines and get people travelling as the travel sector suffers under the strain of the pandemic.
But the transport secretary dismissed this idea, saying: "One of the things that people don't realise with testing is if you test somebody who's asymptomatic, they don't have any signs of coronavirus on day one when they arrive in an airport.
"That would only pick up 7% of people who actually did have the disease, which isn't useful from the point of view of making sure that you get the cases.
"You have to then test again later and that brings in further complications about ensuring that people have quarantined in the meantime and that doesn't work either."
Travel firms have been hit hard by the UK's quarantine decision, with Ryanair boss Michael O'Leary calling it a "badly-managed overreaction" and TUI extending holiday cancellations until 4 August.
And holiday operator Jet2 says it has "taken the decision to suspend flights and holidays to Tenerife, Gran Canaria, Fuerteventura, Lanzarote, Majorca, Menorca and Ibiza up to and including 9 August".
The company said it had already suspended flights and holidays to Costa de Almeria, Alicante, Malaga and Murcia up to and including 16 August, and said its staff will be contacting customers already in those locations "to advise them of their options regarding flying back to the UK" and urged customers not to contact them.
People due to travel to these destinations with Jet2 after the dates above will be updated "once we receive more information from the government", the operator added.