Hajj specialist travel firm OneCall Travels has ceased trading as an Atol holder.
The London-based company also traded under the website names www.onecalltravels.co.uk and www.onecalltravels.com.
The Civil Aviation Authority posted the failure on its website.
The regulator said: “We are currently collating information from the company and will update this page as soon as possible.
“Whilst waiting for further information, please do not use claim forms from other failures as these cannot be accepted.”
The OneCall Travels website was still live today, saying the firm has been providing Hajj and Umrah services since 2004.