Holidaymakers could face quarantine on return to Britain under new 'red list' alert system

Holidaymakers due to travel abroad have been warned that they could be forced into quarantine on their return under a new system that could see "air bridges" collapse at short notice.

The UK currently reviews nations on its "safe list" every three weeks but is expected to announce a rolling review system that could see countries placed on its "red list" at short notice should they see a serious spike in coronavirus cases.

It raises the prospect of holidaymakers travelling abroad to countries only to discover, before they end their holiday, that they may have to stay in quarantine on their return.

The Government is expected to announce that Spain is to remain on its "safe" list despite a surge in Covid-19 outbreaks that has forced regional authorities to reintroduce local restrictions.

However, it is understood that ministers intend to replace the three-weekly review of "safe" destinations with one in which countries are added or excluded depending on spikes or drops in cases.

That will allow a more agile response to open up countries to travel as their infection rates fall and exclude those hit by a second wave, even though holidaymakers could face a period of quarantine on their return.

The review is understood to make very few changes to the 74 destinations exempted from the 14-day quarantine in the first list of "safe" countries three weeks ago.

Portugal, which was controversially left out, remains fearful it will not be added to the list despite an intensive lobbying campaign.

Rita Marques, Portugal's tourism minister, said she was concerned the country's "red list" status would not change if the UK Government kept using the same infection rate criteria as before.

Manuel Lobo Antunes, Portugal's ambassador, warned that the economic damage caused from effectively killing off the entire UK summer holiday trade would be "immense and lasting". Portugal confirmed 229 new virus cases on Thursday, of which just 10 were in the Algarve.

Ministers have also set up a special Whitehall group to investigate how testing could be introduced either at UK airports or before arrival to open up travel with countries still with lockdowns.

It is unlikely before the autumn, but could enable arriving passengers to sidestep quarantine by testing negative for the virus.

Heathrow has offered to host a trial of the PCR testing equipment with Swissports, a ground-handling company, and Collinson Group, medical specialists.

The Department for Transport (DfT) is also considering regional "air bridges" which would allow travel to "low-risk" regions such as, for example, the Algarve, Madeira and the Azores but exclude Lisbon, which accounts for most of Portugal’s new cases.

Spain has been hit by outbreaks in Catalonia, Aragon and the Basque region with 2,615 new cases on Thursday, compared with a daily average of just 132 in June.

One town in south-east Spain was closed off on Thursday after 55 people who met at a bar tested positive for coronavirus. Authorities in Totana, Murcia, which has 32,000 inhabitants, were testing 300 people who were at a bar at the time of the outbreak on Wednesday.

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Further north, the Catalan regional government is considering restricting people from going out at night in Barcelona to stop young people spreading the disease. Four million people in Barcelona and outlying towns were asked to stay at home to try to contain a surge in cases on Friday.

The surge in cases has prompted scores of British holidaymakers to cancel at the last minute, tourist authorities said.

Elizabeth Keegan, the director of tourism in Lloret de Mar, a resort 48 miles north of Barcelona, told The Telegraph: "We are getting cancellations from Britain, France and Belgium. The 120 hotels here are about 65 per cent full and they are normally 100 per cent full at this time of year.

"We are getting calls from Britain asking if we are in Catalonia because they have heard the news about the cases in Barcelona."

Madrid is pushing the central government to impose stricter controls on Barajas airport after more than 70 passengers landed in the capital while infected. Madrid authorities have also urged citizens to wear a face covering even at home when they are with people with whom they do not live.

Promoting a similar message, the Canary Islands launched a graphic publicity campaign in which a family party turns to tragedy when the grandfather ends up unconscious in hospital after contracting Covid-19. "A simple family gathering can bring you as a present 40 days in a coma, or even death," the slogan reads.

Failing to bring the epidemic under control could spell disaster for Spain's tourism sector, which accounts for some 12 per cent of economic output and has begun a tentative reopening after hotel occupancy more than halved in the first six months of the year.