Ryanair and Manchester Airports Group (MAG), which owns Manchester, Stansted and East Midlands airports, will call for more transparency over how Whitehall decides which countries are on the green, amber and red lists.

The action was last night backed by AGS Airports – the owner of Glasgow, Aberdeen and Southampton airports.

Chief executive Derek Provan confirmed his company was not a direct participant in the legal action, but fully supported the move, adding: “Throughout this pandemic we have heard government state on numerous occasions that it is working with the aviation industry.

Passengers at Edinburgh Airport. Picture: Lisa Ferguson

“The fact it has taken a legal challenge from our industry colleagues to call for greater transparency around the traffic light system is a clear indication that there continues to be fundamental lack of engagement.

The initial plans for the safe restart of aviation in May and to rebuild already fragile passenger confidence collapsed following the decision to move Portugal to the amber list.

"Yet we have no understanding of the reasoning behind this decision – one that has dealt a catastrophic blow for an industry already on its knees."

The backing came as as the UK Government confirmed it was considering plans for vaccines to play a role in opening up international travel.

The government is understood to be drawing up changes to the traffic light system for international travel in a bid to save summer holidays.

People who have had both Covid jabs may be able to avoid quarantining on their return from amber-list countries under the new plans.

But any decision may yet only apply to those travellers returning to England rather than Scotland.

While the Scottish Government’s traffic light list has generally matched that set by the UK Government, authorities have at times deviated north of the border on which foreign countries are classed as ‘green’, ‘amber’ or ‘red’.

A Scottish Government spokesperson said: “We aim to come to a four nations position on international travel restrictions wherever possible.

“However our current position remains international travel for holidaying purposes remains risky and subject to sudden change. We have said before people should think very carefully about travelling – especially so given the prevalence and unpredictable nature of variants of concern.”

The quarantine and coronavirus testing requirements people face when returning to the UK are based on a traffic light system.

Before the system was introduced, the Department for Transport said assessments would be based on a range of factors, including the proportion of a population that had been vaccinated, rates of infection, emerging new variants, and access to reliable scientific data and genomic sequencing.

But the movement of Portugal from green to amber led to accusations that decisions were being based on political rather than public health motives.

There are no major viable tourist destinations on the quarantine-free green list, with the most popular countries in the amber tier.

People returning to the UK from an amber country must self-isolate at home for ten days, take a pre-departure test and two post-arrival tests.

The move being considered by the UK Government would effectively render amber countries green for the fully vaccinated, opening up quarantine-free travel to most holiday destinations in Europe and the US.

Downing Street said the government wanted people to travel abroad “as soon as it is safe to do so”, but stressed that no decisions had been made about opening up holidays for those who had received both vaccine doses.

The Prime Minister’s official spokesman told a Westminster briefing: “As we have always set out, we want people to be able to travel abroad as soon as it is safe to do so.”

The spokesman said the current traffic light system was the “right approach … at this stage of the pandemic”, but that ministers would keep measures under review.

The next wider UK travel review is expected to take place on June 24, with any developments coming into effect early the following week.

First Minister Nicola Sturgeon has said she will next week review the Covid restrictions in place, although she has flagged there is “unlikely” to be any easing of lockdown in any part of the country from June 28.

Just 11 countries are currently on the green list, including Australia, Iceland and Israel. People returning to the UK from those destinations do not need to quarantine upon arrival.

Jesse Norman, the financial secretary to the Treasury, said the government was “certainly looking at all the options”.

He told Sky News: “We don’t want to get left behind by countries, which may be adopting a two-jabs approach if it can be done safely.”

However, he said the prospect of unvaccinated under-30s missing out on summer holidays was “certainly a consideration to be borne in mind”.

Commenting on the legal action announced on Thursday, Ryanair boss Michael O'Leary said: "The UK's traffic light system has been a complete shambles from the beginning.

"This go-stop-go-stop policy is causing untold damage to the aviation industry and frustrating and upsetting millions of British families when they see their holiday plans and family visits disrupted by the government's mismanagement of international travel.

"We call on Prime Minister Boris Johnson to explain the scientific basis behind this system that the government seem to make up as they go along, and to establish a data-driven transparent model that could restore confidence in air travel ahead of the very crucial peak summer months."

It is understood several major UK airlines would support the action, in which health secretary Matt Hancock and transport secretary Grant Shapps would be named as the defendants.

Mr “Whilst not a direct participant of this legal challenge, we fully support it.

“Throughout this pandemic we have heard government state on numerous occasions that it is working with the aviation industry.

MAG chief executive Charlie Cornish said the travel sector recognised "the critical importance" of protecting public health, but added the UK Government appeared to be "unwilling to open up international travel by putting low-risk countries on the green list".

He went on: "The government is not being open and we simply cannot understand how it is making decisions that are fundamental to our ability to plan, and to giving customers the confidence to book travel ahead.

"These issues must be resolved urgently – and ahead of the review point later this month – to allow everyone to understand how the system operates, and to create the opportunity for international travel to resume to the fullest extent possible over the summer."

Labour shadow transport secretary Jim McMahon said: "Labour has repeatedly called for ministers to publish the data and criteria around their traffic light system – yet they refuse to do so."When will they deliver on the sector-specific support promised for aviation 15 months ago? It's now clearer than ever that this government is actively choosing to turn its back on the industry at a time when thousands of jobs are on the line."

Responding to reports the UK Government had begun to "consider the role of vaccinations" for inbound travel, Steve Heapy, boss of airline Jet2.com and tour operator Jet2holidays, described the development as "very welcome news".

He expressed hope it would lead to a "meaningful restart to international travel in the very near future", adding: "The vaccination programme was designed to protect people from coronavirus so that they can enjoy their freedoms once again.

"If people have received two doses of the vaccine and are still not allowed to travel overseas to enjoy their holidays, what is the purpose of the vaccination programme?

"The rollout has been a huge success, so it is time for us all to enjoy the benefits of that."

He added: "At present, the UK remains largely grounded and our customers are left to look on with envy whilst the rest of Europe opens up."

Scottish airports back legal action as quarantine-free travel considered for UK travellers with two Covid vaccine doses

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