Walsh said capacity caps, such as the 100,000 passenger a day limit enforced by Heathrow last month, risked leaving airlines in a position where they are unable to convert two years of pent-up travel demand.

Former boss of BA parent IAG Walsh said Heathrow’s yet-to-be-published June service level performance data would likely show "the lowest level of service by the airport since records began".

“By capping passenger numbers, airports are preventing airlines from benefitting from the strong demand," said Walsh. "Heathrow airport has tried to blame airlines for the disruption. However, service level performance data for the first six months of this year show they have failed miserably to provide basic services.

"Data for June has not yet been published but is expected to show the lowest level of service by the airport since records began."

Walsh also cautioned the European Commission against reinstating its 80:20 slot usage rule too quickly, despite the easing of Covid travel restrictions releasing "a torrent" of pent-up travel demand.

"At the same time, meeting that demand has proved challenging and likely will continue to be so," said Walsh. "All the more reason to continue to show flexibility to the slot use rules. The European Commission’s intent to return to the longstanding 80-20 requirement is premature.

"Just look at the issues that airlines and their passengers at some hub airports are being confronted with," Walsh continued. "These airports are unable to support their declared capacity even with the current 64% slot threshold and have extended recent passenger caps until the end of October. Flexibility is still essential in support of a successful recovery."

Walsh’s comments came as Iata revealed global air travel had now recovered to 70.8% of pre-pandemic levels, with international travel within Europe "above pre-pandemic levels in seasonally adjusted terms".

TTG has approached Heathrow for comment.