The warning comes as United Airlines continues to face a customer backlash after Dr David Dao was dragged off Flight 3411, suffering a broken nose, concussion and losing two teeth during the incident.

It has since emerged that just a day later easyJet also ordered two passengers off a plane after overbooking the flight, and then allegedly failing to inform them of their denied boarding rights, including the €400 owed to each of them.

EasyJet later apologised, stating: “We are very sorry about the situation that the couple have experienced… This has neither been handled well enough to meet our standards or our policy, which is compliant with EU261 regulations.”

Kevin Clarke, head of the Flight Delay Team at Bott & Co Solicitors, told TTG he had seen a notable rise in the number of claims from passengers alleging denied boarding, which he said indicated that airlines were failing to inform passengers of their rights under EU Regulation 261 (see box, right).

“In 2016, we had 100 denied boarding claims – this year so far we’ve had 159 claims alone, and we haven’t even had the busiest months of the year,” he said. “We anticipate that by the end of the year we’ll have seen a 400-500% increase.”

Clarke conceded that the rise could in part be attributed to passengers’ increased awareness of their rights, but he added: “There’s no dispute regarding [regulation] 261. If you are denied boarding and the passenger has turned up in a fit state, there has to be compensation, and airlines clearly aren’t informing customers of this or we wouldn’t be getting these claims.”

It comes as marketing experts branded United Airlines’ response to last week’s incident a PR “catastrophe”.

Sarah Rathbone, managing director of Siren Communications, said the airline faced “a huge challenge in having not acted fast enough”.

Steve Dunne, executive chairman at Brighter Group, added: “United’s response was a textbook example of how not to do things… This incident will haunt United for decades to come.”