For many years, online travel agents have urged holidaymakers to buy flights and accommodation together in a single transaction.

Yet suddenly one of the largest, Expedia, appears to have changed its tune, with a new and widely broadcast television advertisement for a scheme called “Add-On Advantage”

But holidaymakers who act on the ad will find they have far fewer consumer rights than when booking flights and accommodation in the same transaction.

Package holiday rules changed on Sunday 1 July to give travellers who book through online travel agents much more protection. The basic principle: if flights and accommodation are sold at the same time, the travel company must take full responsibility for providing the holiday as booked.

Previously online travel agents had shunned any such duty, saying that they simply provided a booking platform and that holidaymakers had contracts with the individual suppliers.

The new rules are designed to provide up to 10 million British travellers a year with extra protection.

But there is a loophole through which agents can escape liability. If flights and accommodation are booked separately, the purchase is known as a “Linked Travel Arrangement” (LTA) and has only very limited financial protection.

Critics in the travel industry say that the Expedia campaign appears intended to steer holidaymakers towards LTAs, without mentioning that their consumer rights will be greatly diminished.

The ad, screened during Love Island and the Croatia v Denmark World Cup match on Sunday, says:

“A hotel can make or break a trip, and at Expedia we don’t think you should be rushed into booking one. That’s why we created Expedia’s Add-On Advantage.

“Now, after booking your flight, you unlock discounts on selected hotels for your trip that are available right until the day you leave.”

Derek Moore, chairman of the Association of Independent Tour Operators (AITO), said: “A true tour operator not only provides full financial protection, but also takes full responsibility for all aspects of its holidays and for the actions of its suppliers.

Tempting prospect? A still from the new Expedia television ad, urging holidaymakers to book their flights first and their hotel later (Expedia)

“Expedia has walked away from any such responsibility. There is nothing illegal about what they are doing but they are cynically encouraging the consumer, for no good reason, to lose out on all that gold-plated consumer protection.

“The average consumer won’t of course realise this until they need the missing protection. Expedia will save a lot of money, but is behaving in a very irresponsible way.”

Ted Wake, director of Kirker Holidays, said: “Expedia’s latest marketing campaign conceals the fact that they are seeking to encourage consumers to commit to buying an holiday with inferior levels of protection.

“If you were to draw parallels with forecourt car sales, it would be equivalent to a major manufacturer using market muscle to discount cars – but at the same time disabling the airbags and removing seat belts.

“Consumers need clear messages, and are entitled to fully protected holiday packages.”

In a statement to The Independent, Expedia said: “We know from research and what we see on our site that a good deal of people want to book their flight or car first, then come back and book their accommodation at a later date.

“We see the Expedia Add-On Advantage as a bonus for people who require time and flexibility to book their trip.

“Our website footers and booking terms and conditions provide clear information to consumers on the level of protections that they have depending on the travel products that are booked.”

Online travel agents are unhappy about the change in legislation. While the EU Package Travel Directive was published in 2015, the new UK law was published only 10 weeks ago.

One leading company, Sunshine.co.uk, kept its old terms and conditions in place for over 24 hours after the new rules took effect, insisting it accepted “no responsibility or liability” if anything went wrong with the services provided by suppliers such as airlines or hotels.

The firm blamed a technical problem, saying: “Updated terms were in place by 10am on Monday 2 July. All bookings made with Sunshine from 1 July are subject to the updated terms and customers have received these new terms as part of their booking confirmation.”

ABTA, the travel association, has criticised the late publication of the Package Travel Regulations for making life difficult for businesses.

A spokesperson for ABTA said: “Customers should rest assured that, for holidays booked on or after 1 July, the new regulations apply giving them all the rights intended under those regulations whether or not the travel company has updated its booking conditions.”