EasyJet, which created the ad in-house, attempted to defend itself by saying that seats normally started off at their cheapest price, before rising as the departure date approached, but stressed a discount was still offered on all flights.

The ASA acknowledged that discounts were offered on each day of the promotion, but also noted that towards the end of the campaign some customers were forced to pay more for flights than if they had booked tickets before the promotion began.

The advertising regulator considered that most customers would expect fares to be cheaper during the promotional period and so found the campaign in breach of several codes.

EasyJet has been told not to use the same claim again and to make it clear in future executions that although initially discounted, prices may also rise during the promotional period.

The ruling comes as rival airline Ryanair is in the process of taking the ASA to the Office of Fair Trading (OFT) for what it considers to be “unfair procedures, bias and factually untrue rulings” over the last two years.

Separately, Scottish Gas, part of British Gas, has also been rapped by the ASA this week for falsely comparing its prices against Scottish Power in a radio ad.

The energy provider claimed its duel fuel package was cheaper than its rival, however omitted to include information about a ‘prompt payment discount’ Scottish Power offers that could in fact make its prices cheaper.