A watchdog has released a “red list” of 20 package holiday providers that people are advised against booking a trip with.

Which? has issued the advice based on company’s “shortcomings” with refund commitments due to COVID-related disruption.

It said the companies that could leave holidaymakers out of pocket if they are unable to travel as planned include major operators Lasminute.com, Love Holidays, On The Beach and Teletext.

Those that did not provide clear information on their booking policies were also rated as red for a lack of transparency.

In response, On the Beach said: “If the FCDO advises against travel to a destination, our customers can change their holiday destination or dates free of charge, and we will waive any of our admin fees.

“If they wish to cancel their holiday, we will fully refund hotel and transfer costs, and our regulated, ring-fenced trust account means that we are able to do this quickly and always in cash rather than credit notes or vouchers.

“Our holidays include flights from multiple third-party airlines and the decision on whether to operate those flights lies with each airline.

More on Covid-19

It added: “If the airline cancels the flight, then we will, of course, pass the refund straight on to our customers in full.

“If a customer wishes to cancel their holiday due to FCDO advice, but the flight operates as planned, the airline retains the monies paid for the flight, and in those instances, this leaves us unable to pass a refund on to our customers.”

The policies of operators on the red list were not necessarily in breach of consumer law but some have faced investigations by the Competition and Markets Authority (CMA) in the past year over failures to refund their customers, such as Love Holidays and Teletext, Which? said.

Each company’s policies on coronavirus-related disruption, including whether it would refund customers if a lockdown was imposed, if Foreign Office advice changes, or if they have to quarantine in a hotel on their return, were considered by Which?

Companies that committed to offering refunds in most scenarios put to them by Which? included British Airways Holidays, First Choice, Hays Travel, Jet2 Holidays, Trailfinders and Tui.

Only three providers – Exodus, Explore and Discover Egypt – guaranteed customers refunds in the event someone was told to self-isolate before they travel as well as all the other scenarios put to them.

The consumer group is advising anyone considering a holiday to avoid booking with one of the companies placed on the red list and to check their provider offers a good flexible booking policy beforehand.

Which? travel editor Rory Boland said: “Between changing travel restrictions, both in the UK and abroad, and the ongoing risk of being told to self-isolate, booking a foreign trip still comes with some uncertainty and things can go wrong if you’ve chosen the wrong provider.

“The best companies won’t leave you high and dry though, so it’s vital to do your research before booking.”

The watchdog said it would regularly evaluate providers and update its lists accordingly and people can check their provider against the list via the Which? Holiday Checker.