Iata said the UK’s decision to re-impose quarantine restrictions for Spain had contributed to weakened consumer confidence as the association predicted it would take a year longer than projected for airline traffic to return to pre-Covid-19 levels.

The association said the recovery in aviation traffic in the wake of the coronavirus pandemic had been slower than expected and predicted it will take until 2024 for revenue passenger kilometres to return to pre-pandemic levels.

Overall passenger numbers were likely to recover slightly faster than overall kilometres based on the earlier return of short-haul travel, but Iata has also pushed its projection for a full return back by a year from 2022 to 2023.

The association predicts that 2020 global passenger numbers will decline by 55% compared to 2019, having previously forecast a 46% drop.

It said the more pessimistic outlook was based on trends including the slow containment of the virus in the US and developing economies, reductions in corporate travel and weak consumer confidence.

It also warned that while scientific advances in fighting Covid-19 could allow for a faster recovery, present trends suggested there was “more downside risk than upside” to its baseline forecast.

Alexandre de Juniac, chief executive, said: “Passenger traffic hit bottom in April, but the strength of the upturn has been very weak. What improvement we have seen has been domestic flying. International markets remain largely closed.

“Consumer confidence is depressed and not helped by the UK’s weekend decision to impose a blanket quarantine on all travellers returning from Spain. And in many parts of the world infections are still rising. All of this points to a longer recovery period and more pain for the industry and the global economy.”

Reiterating calls for a continuation of slot waiver agreements to reduce pressure on airlines to fulfil commitments, de Juniac added: “For airlines, this is bad news that points to the need for governments to continue with relief measures—financial and otherwise.”