More than 8,000 passengers are stranded around Europe and the Mediterranean after banks pulled the plug on German charter airline Aero Lloyd.
The now-insolvent carrier is 66%-owned by BayernLB, the Bavarian state bank.
But on Thursday the bank said it would no longer underwrite Aero Lloyd.
Passengers booked through travel agencies would have to be re-booked onto other airlines, Aero Lloyd said, while those it had booked itself would have to make their own arrangements.
Of the 8,500 customers which Aero Lloyd said were left stranded by its decision to cease operations at 0400 GMT on Thursday, 4,000 were waiting at German airports.
Another 4,500 are stuck in foreign countries, including about 1,000 booked through Thomas Cook on holidays in Greece and Egypt.
Thomas Cook said it was seeking alternative flights to get its customers home, while German travel group TUI said it was working with its other partners to make alternative arrangements for its 1,300 stranded customers.
Aero Lloyd, which was founded in 1981 and has 1,400 staff, flew to 60 destinations in 13 countries using a fleet of 20 Airbus aircraft.
BayernLB took a stake in the company in 1987, and had been underwriting a restructuring.
But that plan has now been rejected, Aero Lloyd said.
"Despite an extensive three-year redevelopment and restructuring concept from the new Aero Lloyd management... BayernLB has now decided not to take the necessary capital measures to stabilise AeroLloyd's balance situation," the airline said in a statement.