Industry sources warn of an “almighty battle” to get quarantine restrictions lifted after the government scrapped travel corridors and demanded arrivals show proof of a negative pre-departure Covid test from Monday.

The new border regime came in alongside tighter checks and a tightening of exemptions to quarantine.

E-passport gates were closed at Heathrow to ensure passengers produce Covid-test results, with £500 fines for those without.

Airlines are expected to deny boarding to passengers without proof of negative tests. An airline source confirmed: “This is challenging to implement. They’re tightening the exemptions and stepping up checks.”

Government guidance does not specify the type of pre-departure test required, only its sensitivity, but makes clear: “It’s the passenger’s responsibility to ensure the test meets minimum standards.”

The source said: “Passengers will depend on test providers to ensure tests comply. We see it as predominantly a PCR-test requirement, but people will get confused. Language will be a problem. There are certain to be passengers denied boarding.”

The test result is required three days before departure, not 72 hours as widely reported by ministers and the media. The source confirmed: “It’s definitely three days. A passenger could take a test on Tuesday morning and fly on a Friday night.”

Once the new regime has bedded in, the source said: “The priority will be to look at a pathway out of this. Our preference is to keep the tests and remove quarantine, but that is going to be an almighty battle. It’s going to be a long process. We need to understand what restrictions will be lifted first.”

An aviation source warned there is little chance of an early relaxation of quarantine, saying: “We recognise this is a public health emergency. It’s not realistic to lift quarantine.”

The source also noted: “We’re slightly ahead of the curve on the vaccine rollout. The UK economy may be able to reopen in the second quarter. We may be able to go to the pub, but there might still be travel restrictions. Some countries might not let Brits in or we may look at other countries and ban travel.

“How do we give the public confidence we’re not reimporting the virus? We need a framework for a divided world. But that is Stage 2. Stage 1 is to get through this crisis.”

Boris Johnson announced the abandonment of travel corridors last Friday, after initially removing them for 16 countries due to the variant found in Brazil. The PM said closing corridors would “protect against the risk of new strains” of Covid-19.

Media reports suggest a further tightening is in prospect with officials studying New Zealand’s ‘quarantine hotel’ system which sees arrivals directed to quarantine in hotels for two weeks at their own expense.

The airline source noted quarantine hotels “have not been discussed with the industry” and said: “It works in a country the size of New Zealand. We’re not sure it would work in the UK.”

Newspapers reported that ministers will hold talks on Friday about accelerating plans for quarantine hotels among further border control options due to rising concern about the risk of travellers importing variants of the virus.