On Tuesday (12 July), the airport introduced a daily cap on passenger numbers for the remainder of the summer. It limited passengers to 100,000 a day – a reduction of 4,000 a day on current numbers. 

In response to the move, Emirates said Heathrow gave it 36 hours to comply with the cuts, which the carrier said appeared to be a "figure 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," a spokesperson said. "This is entirely unreasonable and unacceptable, and we reject these demands.

"At Heathrow, our ground handling and catering – run by dnata, part of the Emirates Group – are fully ready and capable of handling our flights. So the crux of the issue lies with the central services and systems which are the responsibility of the airport operator."

The airline has reinstated six daily A380 flights from Heathrow since October 2021, "so our operational requirements cannot be a surprise to the airport," the spokesperson continued.

"Now, with blatant disregard for consumers, they wish to force Emirates to deny seats to tens of thousands of travellers who have paid for, and booked months ahead, their long-awaited package holidays or trips to see their loved ones."

Emirates said rebooking the "sheer numbers" of potentially impacted passengers would be "impossible" with all flights running full for the next weeks, including at other London airports and on other airlines. It also said moving passenger operations to other UK airports was "not realistic".

In response, a Heathrow spokesperson said a key issue contributing to delays was 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”.

The spokesperson added: “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.

“It would be disappointing if instead of working together, any airline would want to put profit ahead a safe and reliable passenger journey.”

Meanwhile, Clive Wratten, chief executive of the Business Travel Association, said: "The Heathrow passenger cap is an outrage for business and leisure travellers. The arbitrary daily passenger number has been selected without consultation with airlines and the wider travel community.

"This is a betrayal of all UK travellers, leaving airlines, travel management companies and travel agents to pick up the pieces. Heathrow must be transparent about their problems and offer support for the airlines and travellers this impacts."