The owner of Manchester, Stansted and East Midlands airports has reportedly teamed up with Ryanair to launch legal action against the Government over its international travel traffic light system.
The risk-based system with red, amber and green ratings for different countries determines the quarantine and coronavirus testing requirements people face when returning to the UK.
The legal action to be brought by Ryanair and the Manchester Airport Group will call for more transparency over how Whitehall decides which countries qualify for the green list, the PA News agency has said.
An industry body warned on June 9 the "failed and damaging" system for international travel must be abandoned if the UK travel and tourism sector is to be saved from total collapse.
The London-based World Travel and Tourism Council (WTTC) said the Government must scrap the system, which has "wreaked havoc" among consumers and businesses, in order to save hundreds of thousands of jobs.
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."
PA understands that several major UK airlines will support the action, in which Health Secretary Matt Hancock and Transport Secretary Grant Shapps will be named as the defendants.
MAG chief executive Charlie Cornish said the travel sector recognises "the critical importance" of protecting public health, but added the Government appears 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."
A Government spokeswoman confirmed work had begun to "consider the role of vaccinations" for inbound travel following the continued success of the jab's rollout.
This could mean the return of holidays to popular summer hotspots such as Spain, Portugal, France and Italy, all currently on the UK's amber list.
Demand for air travel collapsed in March last year when the UK went into lockdown in response to the crisis, with the Government now under pressure to restart international travel by the battered tourism industry.
