The UK government is poised to put more countries on its quarantine list "straight away" if coronavirus runs "out of control" in them.
Culture Secretary Oliver Dowden told Sky News more announcements could follow the decision to advise against all non-essential trips to Spain over the weekend due to fears over rising levels of COVID-19.
"It would be foolhardy of the government not to impose those restrictions if we think there is a risk and we will impose those restrictions as soon as we think the risk has materialised," he said.
"We cannot risk importing it again from other countries where incidences are rising."
Mr Dowden added the decision to announce any new restrictions will be taken after an assessment by the Joint Biosecurity Centre - set up at the start of the outbreak - and England's chief medical officer.
"We are at a very risky moment with this pandemic," he said.
"So long as you're aware of that risk and comfortable with that risk, go ahead and take your break."
But he added: "If we know that risk is there we will impose those restrictions straight away."
Belgium, Luxembourg and Croatia are being looked at by ministers given the rates of coronavirus there, the Daily Telegraph reports.
Mr 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" from are of most concern.
Madrid has been lobbying for the UK to make regional exemptions for travellers from areas with much lower levels of coronavirus - such as Balearic and Canary islands.
A minister revealed on Tuesday the plan is under consideration but cautioned "we are not there yet".
Jose Ramon Bauza, a former president of the Balearic islands, said he "doesn't understand the decision of the British government" to change its travel advice on Spain.
"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."
Travel firms have been hit hard by the UK's decision, with Ryanair boss Michael O'Leary calling it a "badly-managed overreaction" and TUI extending holiday cancellations until 4 August.
Meanwhile, New Zealand is reportedly planning to start charging tourists up to $3100 (Â£1,591) for the cost of their stay in hotel rooms where anyone arriving must quarantine.
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.