Emirates on Thursday said it will ignore an order from Heathrow Airport for it to cancel flights to comply with a cap on passenger numbers.
The west London airport told carriers earlier this week to stop selling summer tickets as it imposed a limit on passenger numbers until September 11.
Passengers flying to and from the UK’s busiest airport have suffered severe disruption in recent months, with long security queues and baggage system breakdowns.
But the airline responded on Thursday and accused Heathrow of showing “blatant disregard for consumers” by attempting to force it to “deny seats to tens of thousands of travellers”.
In a statement, Emirates said: “LHR (London Heathrow) last evening gave us 36 hours to comply with capacity cuts, of a figure that appears to be plucked from thin air. Their communications not only dictated the specific flights on which we should throw out paying passengers, but also threatened legal action for non-compliance.
“This is entirely unreasonable and unacceptable, and we reject these demands.” It added: “Until further notice, Emirates plans to operate as scheduled to and from LHR.”
Responding to Emirates' refusal to cancel flights, a Heathrow spokeswoman said: "Aviation is a complex network and no-one can operate in isolation. The network continues to suffer from Covid-related challenges.
"While many factors have resulted in the delayed flights, misconnected bags, long waits for arriving bags and last-minute cancellations at Heathrow and airports across Europe in recent weeks, a key issue is airline ground-handling teams which are currently only resourced up to 70% capacity to serve passenger demand which has returned to 80-85% of pre-pandemic levels.
"For months we have asked airlines to help come up with a plan to solve their resourcing challenges, but no clear plans were forthcoming and with each passing day the problem got worse.
"We had no choice but to take the difficult decision to impose a capacity cap designed to give passengers a better, more reliable journey and to keep everyone working at the airport safe.
"We have tried to be as supportive as possible to airlines and our 100,000 cap on daily departing passengers is significantly higher than the 64,000 cap at Schiphol (in Amsterdam).
"It would be disappointing if instead of working together, any airline would want to put profit ahead a safe and reliable passenger journey."
The row came as it was claimed that travellers who pay extra money to speed up passport applications are being “fleeced” as there are no guarantees they will arrive in time.
With demand for new passports soaring as thousands look to book holidays after the end of Covid restrictions, the Passport Office has told applicants they should expect to wait up to 10 weeks.
Labour on Thursday said some people are being asked to pay £66 to expedite applications. Shadow transport secretary Louise Haigh said the Government “are fleecing people out of their hard-earned cash just to get their passport fast-tracked — with no cast-iron guarantee that they will still get it back in time.”
A Home Office spokesperson said “the vast majority of passport applications continue to be completed well within the 10-week guidance”.
On the claims some applicants were encouraged to pay extra to speed up the process, the spokesman said: “Customers will only pay for an urgent service where they need a passport sooner than 10 weeks.”