The Competition and Markets Authority (CMA) opened enforcement cases into both carriers in June to establish whether either had broken consumer law.

But, on Thursday (7 October), the body concluded that a "lack of clarity" in the law makes it "insufficiently certain" that it would be able to secure refunds for the airlines’ customers who were prevented from flying because of Covid restrictions.

According to the CMA, consumer protection law sets out that passengers are entitled to refunds when an airline cancels a flight, because the firm cannot provide its contracted services.

However, it does not clearly cover whether people should be refunded when their flight goes ahead but they are legally prohibited from taking it.

Following its review of the law and evidence, the CMA concluded that prolonging this investigation "could not be justified" given the length of time it would take to reach an outcome in the courts and the uncertain result.

Andrea Coscelli, chief executive of the CMA, said the authority "strongly believes" that people who are legally prevented from taking flights due to lockdown laws should be offered a full refund.

BA had offered customers vouchers or rebooking and Ryanair provided the option to rebook.

"However, after considering the relevant law and gathering evidence in our investigation, we have concluded that the length of time that would be required to take this case through the courts, and the uncertain outcome, can no longer justify the further expense of public money," Coscelli added.