Willie Walsh, the chief executive of British Airways parent IAG, has disclosed that the group is considering legal action over the UK government’s mandatory two-week quarantine for travellers arriving in the country from 8 June.

“It’s terrible, I wrote to MPs [members of parliament] last night to say that this initiative has torpedoed our opportunity to get flying in July,” Walsh told Sky News on 5 June. “We think it’s irrational, we think it’s disproportionate, and we are giving consideration to a legal challenge to this legislation so we are reviewing that with the lawyers later on today.”

He added: “I suspect there are other airlines who are doing so because it’s important to point out there was no consultation with the industry prior to enacting this legislation and we do believe it’s an irrational piece of legislation.”

Ryanair is backing the move to bring the quarantine before the courts, telling Cirium that it would “support any legal action launched by IAG against the UK’s ineffective and useless visitor quarantine”.

The Irish carrier’s chief executive Michael O’Leary has criticised the UK government’s plans, arguing that they make little sense and have been badly prepared. “You don’t have a quarantine,” he told the BBC on 4 June. “People are going to be allowed to come in through Heathrow and Gatwick, they then get on the London underground, the trains, taxis to get to their destination, they can go to the supermarket… There is no quarantine.”

Relations between the airline industry and the UK government have soured over the quarantine plan. IAG reportedly refused to attend a 4 June meeting with UK home secretary Priti Patel to discuss the plan, although the group has declined to comment.

EasyJet says that it did attend the meeting with Patel but would provide no further details. It adds that the UK quarantine will “severely restrict Britain’s connectivity and delay both economic and social recovery. A risk-based approach needs to be taken and the government needs to put air bridges in place to remove quarantine for travellers from countries where Covid-19 is under control and effective health measures are in place.”