Holidaymakers will take up to four times longer to process at European airports after new post-Brexit border rules are activated, ministers have been warned.
Aviation chiefs have told Government officials that millions of British fliers face chaos across the Continent when the European Union's 'entry-exit' system (EES) goes live in October.
They fear it will spark huge queues in some European airport arrivals halls and potentially flight cancellations with planes left waiting on the tarmac.
This is because the new system will require passengers to undergo biometric checks, such as registering fingerprints and having a photo taken, to enter the bloc. These details will have to be re-registered every three years.
However, it is feared that many airports - particularly smaller regional hubs with lower budgets - will not have installed the required infrastructure and will be ill-equipped to handle the vast volume of registrations.
Aviation chiefs have warned the government that British travellers could face waiting times up to four times as long at EU airports from October, when new EU rules come into force
The EU rules could prove to be new Prime Minister Sir Keir Starmer's first major test with Brussels, amid calls for him to urge Brussels to delay the scheme's launch
One senior industry source said that processing could go from 30 seconds to 120 seconds at some EU airports once the 'entry-exit' system is introduced
The warning came during a call between industry chiefs and Whitehall officials at the Home and Foreign Office earlier this month, the Daily Mail has learned.
It is understood that on the call with Whitehall officials, Lapland and children potentially not being able to see Santa was given as an example of where chaos could arise.
Second homeowners with properties in more remote locations where they're flying into smaller airports could also be affected.
It could prove to be new Prime Minister Sir Keir Starmer's first major test with Brussels, amid calls for him to urge Brussels to delay the scheme's launch or seek derogations for British travellers.
'It has the potential to cause huge disruption,' one senior industry source said.
'Officials in Government departments have been told that the average processing time could go from about 30 seconds to 120 seconds.
'That might not sound like a lot, but if you've got hundreds of passengers landing it all adds up and you potentially get to a place where you've got huge queues and people can't disembark planes because arrivals halls are full.
'That in turn could lead to flight cancellations if they're sitting on the tarmac for too long because the short-haul carriers have tight turn-around times. Larger airports will probably be ok. It's the smaller ones where you're more likely to have bottlenecks.'
David Jones, a former Tory Brexit minister who sat on Parliament's European Scrutiny Committee, said: 'It's a really major problem which Keir Starmer has got to address as a matter of priority and get a grip of it as there's no sign that adequate steps are being taken to address the issue.
'There should be some form of derogation, at least until adequate facilities have been built up in airports.
'It's not simply the inconvenience to British travellers. It's going to be the fact that a lot of regional economies in Europe are going to be very badly affected by the fact that people will be put off travel because of the disruption.' 'We could see very long queues and an impact on flights.
'It's clearly going to be a problem for a lot of holidaymakers who go to the south of France, where there's lots of small airports - to Bergerac, places like that - and a lot of places in Spain.'
Lapland and children potentially not being able to fly into Finland to see Santa are understood to have been given as an example of where chaos could arise
An app being developed by the bloc would allow travellers to register and upload their biometric data before travel, smoothing any bottlenecks at the border. But it is understood that it will not be ready by October.
Brussels has already delayed the scheme's launch twice. It was initially supposed to come into force in 2022 and it may decide to delay it again. British ports where the border is in the UK, such as Dover, have also been scrambling to prepare themselves for the scheme.
There have been warnings of huge tailbacks at Dover because of the extra time it will take to provide fingerprints and a photograph to enter France.
As it stands, tourists from non-EU countries like Britain who drive through ports to the Continent and don't need visas can simply have their passports assessed and stamped by border guards, keeping traffic flowing smoothly.
For air travellers, Britons will be required to give their biometric data upon landing in Europe as that's where the border is.
The EES system will apply to Britons entering 25 EU countries and four non-EU countries that are part of the bloc's border-free Schengen area.
The system will apply to all nationals of countries that are not in the EU or Schengen when travelling to the 29 countries.
The EU has decided to introduce it to strengthen its borders. A Labour party spokesman said: 'The previous government failed to adequately prepare for the new system that was coming in.
'This is just another example of tory chaos.
'We are now looking into and scrutinising plans to mitigate the impact on businesses and travellers.'
A European Commission spokesman said: 'The Commission is in close contact with the industry representatives, is aware of the concerns expressed so far and will continue the dialogue. 'It is expected that our partners ensure the necessary preparations at all border crossing points.'