British Airways owner IAG may take legal action against the government’s quarantine plans – and has been backed by Ryanair.

The hint was dropped by chief executive Willie Walsh ahead of the 14-day isolation for international arrivals being introduced on Monday.

He also wants trade unions to “engage” with management to ensure the future of BA.

Walsh told Sky’s Ian King Live programme that he is considering a legal challenge against the quarantine and is reviewing the situation with lawyers.

He said the new rules would “torpedo” the airline’s chances of flying in July.

“We think it is irrational, we think it is disproportionate and we are giving consideration to a legal challenge to this legislation,” Walsh added.

It comes as a row intensifies between management and unions over the proposed loss of 12,000 jobs.

Walsh said: “What we’re doing is consulting with the trade unions, with the elected representatives on potential job cuts.

“No decision has been taken in relation to actual redundancies.

“But what we have done is in compliance with the law. There’s a legal obligation on the company to submit these documents to the elected representatives, then to engage in consultations to give everybody an opportunity to try and reduce, mitigate, do anything we can to reduce the impact of the potential restructuring of the business.”

He added: “We want the trade unions to engage with the British Airways management team to represent the people working hard at BA to ensure the airline can have a future.”

Ryanair’s chief executive Michael O’Leary has previously labelled the quarantine as ‘bonkers’  and the airline has suggested passengers “will largely ignore it”.

Following Walsh’s statement, a Ryanair spokesperson said: “Ryanair will support any legal action launched by IAG against this ineffective quarantine.”

A Downing Street spokesperson later declined to comment on the prospect of legal action, and said it was “disappointing” that BA had chosen to boycott a government meeting on quarantine.