A spokesman for the CAA said on Friday: "We were alerted to the fact they were displaying the ATOL logo on their website (yesterday), and were in the process of taking action to make sure any reference to providing ATOL protection was removed from their website. We'll continue to investigate any breach of the ATOL regulations."

The company gave no explanation for its failure on the website, but urged customers to contact aftersales@expressbookers.co.uk.

It is believed the company also sold through the trade. ABTA confirmed the agent ceased trading and said it was "due to insolvency".

"Customers due to travel should have their airline tickets and if so will be able to use them," it said.

"If they have accommodation booked they will need to rebook and contact ABTA's claims handling partner on 01243 218 412 who will help to arrange a refund.

"Customers whose cards were debited twice for the same booking who have not already received a refund from the company should contact their bank or credit card company as the second transaction will be treated as an unauthorised debit."

Express Bookers claimed to offer holidays in over 26 different countries and hundreds of destinations.

"With our huge range of contacts in the travel industry with airlines, hotels, accommodation suppliers and transfer companies we have managed to negotiate some fantastic deals which we pass onto you," it promised customers.

"So we keep prices low, giving you huge savings, leaving you with more money to spend on holiday. Our business plan is simple, to offer you exactly the same flights, hotels and transfers available but for less, so you can create you very own perfect holiday cheaper, with the same quality and service you would expect.