XL Leisure Group, the UK's thrird largest package holiday group has gone into administration.
All its flights have been cancelled and aircraft grounded.
The BBC reports the Civil Aviation Authority as saying 85,000 people could be stranded abroad and 200,000 have made advance bookings with the company.
The XL group runs an airline and owns several travel companies, including Travel City Direct, Medlife Hotels Limited, The Really Great Holiday Company, Freedom Flights and Kosmar Holidays.
A statement on the XL website says the companies ceased trading 'as a result of volatile fuel prices, the economic downturn, and were unable to obtain further funding'.
Customers who booked through XL ATOL bonded tour operators will receive refunds. These companies are:
The Really Great Holiday Company PLC - ATOL 3827
Trading as: Cruise City, Excel Holidays, The Florida Skytrain, Transatlantic Vacations, Travel City Direct and Travel City International
Kosmar Villa Holidays PLC - ATOL 1760
Trading as: Kosmar Holidays
Freedom Flights Limited - ATOL 5296
Trading as: Freedom Flights
Aspire Holidays Limited - ATOL 6536
Trading as: Aspire Holidays
Customers booked with XL Airways Through XL.com or XL Call Centres will only be able to claim a refund if they booked using a credit card.
XL has issued the following help numbers:
CAA helpline: +44 (0) 2891 856 547.
Administrator helpline: From the UK - 0800 068 8991, from Abroad - + 44 208 242 4783
Martin Couzins, managing editor