American Airlines, Emirates, Etihad Airways, Singapore Airlines and Turkish Airlines face scrutiny after the carriers were found to be breaching consumer law in a review it had undertaken out, the UK aviation regulator said.

According to the CAA, more than 200,000 passengers a year using these airlines could be at risk of missing onward connections and therefore incurring delays of over three hours at their final destination.

The airlines’ refusal to pay compensation in these cases “fails to meet the legal passenger rights requirements for flight disruption,” the CAA said in a statement.

Under European rules, passengers are legally entitled to compensation if they arrive at the final destination of their journey more than three hours late – including if they are booked on a connecting flight – unless the delay was due to "extraordinary circumstances".

These rights apply to any flight departing an EU airport, regardless of the nationality of the airline.

According to data compiled by the CAA, Emirates was the “most complained about airline” for non-payment of compensation for connecting flights.

The CAA said it had also began enforcement action against low-cost Spanish carrier Vueling for “failing to comply with the minimum standards for care and assistance” – including a “lack of clear oversight” to check passengers are being looked after within the requirements of the law.

Richard Moriarty, director of consumers and markets at the CAA, said: “Any disruption to a flight is frustrating for passengers, but delays that cause people to miss connecting flights have a particularly damaging effect on people’s travel plans.

“That’s why there are clear laws in place to make sure passengers that experience this type of disruption are looked after by their airline and compensated when the disruption was in the airline’s control.

“Airlines’ first responsibility should be looking after their passengers, not finding ways in which they can prevent passengers upholding their rights. So it’s disappointing to see a small number of airlines continuing to let a number of their passengers down by refusing to pay them the compensation they are entitled to.

“Where we see evidence of passengers systematically being denied their rights, we will not hesitate to take the necessary action to ensure airlines change their policies and their customers get the assistance they are entitled to.”

The CAA said its enforcement action “follows a comprehensive review of airline policies for supporting passengers experiencing disruption.”

The investigation studied the policies of the top 31 airlines operating in the UK, focusing on four areas: care and assistance during disruption; compensation for missed connections; denied boarding and downgrading (comprising situations when passengers are downgraded to a lower seat class).

An Emirates spokesperson said: “As one of the world’s largest airlines, we comply with all legal requirements and regulations as set by the relevant authorities.
 
“The way in which the CAA has communicated this issue is both misleading and unprofessional.

"As the CAA is well aware, the recent EU guidelines on EC 261 are not intended to amend the law. The issue of EC 261’s application to our flights from the UK involving a stopover in Dubai is currently pending before the Court of Appeal.

"We will rigorously defend our position, and challenge the blanket application of EC 261 to every situation, without consideration of context or the safety of our passengers. Emirates, like any responsible airline, puts the safety of our passengers first and to be penalised for this is absurd.
 
“The safety of our passengers and crew always comes first, and many flight delays are caused by factors that are beyond our control and which are not the airline’s responsibility – such as inclement weather, bird strikes, and airport closures.

"We do everything possible to ensure that any disruption caused to our passengers is minimised. In the event of flight delays or cancellations, we always ensure that our customers are looked after.”