Which? wants the regulator to take action to protect passengers and their rights, accusing easyJet of keeping passengers in the dark about their legal right to compensation or to be rerouted with another airline in the event of a cancellation "at the earliest opportunity".

According to Which?, passengers whose flights have been cancelled have instead been directed to the "manage my booking" section of the easyJet website and/or app which only gives the option to rebook onto another eastJet flight.

"Airlines are required by law to offer passengers whose flights they have cancelled rebooking to their destination at the ’earliest opportunity’," said Which?. "Importantly, this means offering them a flight with an alternative airline if that’s the best option."

Which? has previously reported British Airways to the CAA after the airline, it claims, failed to advise passengers of their compensation rights or reroute them using rival carriers.

"Which? understands the aviation regulator has been assessing our evidence and speaking to BA on this matter," it said. "However, nearly three months on, no enforcement action has been taken against the airline."

Last month, the CAA said it would take enforcement action against any airline found to be "systematically" letting consumers down, while transport secretary Grant Shapps has urged airlines to get their houses in order.

The government is proposing to grant the CAA, as well as the Competition and Markets Authority, stronger powers to tackle consumer rights issues and breaches, including giving the CAA to fine airlines.

Which? said government should make it mandatory for airlines operating in the UK to sign up to the Alternative Dispute Resolution so there is a single, statutory-based scheme allowing travellers to exercise their rights.

"The fiasco of domestic and international flight cancellations shows why consumer travel protections must be strengthened, not weakened," said Which? "The Department for Transport should shelve its plans to water down passengers’ rights to compensation when their UK flight is delayed or cancelled. This is a crucial deterrent against airlines cancelling or overbooking flights.

Which? Travel editor Rory Boland said: “EasyJet has treated its passengers appallingly, but this is just the latest example of a systemic problem in the aviation sector – some airlines routinely ignore their legal obligations because they know they won’t face any consequences. With thousands more flight cancellations potentially to come, passengers face a miserable summer unless the CAA and government act on their promises to stamp out consumer rights abuses.

“A major overhaul is desperately needed, so the government must give the CAA stronger powers so it can hit operators with heavy fines when necessary. Ministers should also drop their ill-conceived plans to slash compensation rates for domestic flights.”

EasyJet said it offered a self-service tool allowing passengers to reroute "quickly and easily" on alternative flights when theirs are cancelled, "including the option to fly to/from different airports within the same country".

On re-routing via alternative carriers, easyJet said: “Where we are unable to offer a direct flight on easyJet within 24 hours, customers are able to secure flights by alternative carriers via our customer contact centres. However, we generally advise passengers to book these flights themselves, as this offers more flexibility and is the quickest way to secure a seat on the alternative flight.

“In these circumstances, we reimburse customers for the full cost of the alternative transport. This information is clearly displayed on our delays & cancellations help page.”

EasyJet added: “We clearly inform customers that if there are no easyJet alternative flights within 24 hours, they can book flights via an alternative carrier and we’ll reimburse them in full or they can choose a full refund.

“We clearly inform passengers of their EC261 rights via our notice of rights and delays and cancellations pages on our website, which are provided to customers should their flights be disrupted. Customers are able to submit an expenses claim easily via our expense form. We advise customers to provide itemised receipts to ensure these are processed as swiftly as possible.”

The CAA said: “We thank Which? for its continued engagement regarding compensation. We will review its latest evidence thoroughly and will respond accordingly. We have regularly called for stronger consumer powers, including the ability to impose fines on airlines. This would allow us to take faster action when appropriate and bring our powers in line with other sectoral regulators.”