British travel operator Thomas Cook, which ran hotels, resorts and airlines ferrying 19 million people a year to 16 different countries. It currently has 600,000 people abroad, forcing governments and insurance companies to coordinate a huge operation to bring them all home.
Here is a summary of official responses to the Thomas Cook collapse:
The UK's Civil Aviation Authority (CAA), regulator and government have a fleet of planes ready to start bringing home more than 150,000 British customers abroad over the next two weeks.
French organization Entreprises de Voyage said that about 10,000 French tourists could be affected by the bankruptcy of Thomas Cook.
Norwegian subsidiary Ving said in a press statement that currently 8,685 Norwegians are on its tours.
The Norwegian Travel Guarantee Fund, an insurance scheme that is compulsory for tour operators, issued a statement saying it will ensure any passengers traveling with Thomas Cook's Norwegian unit will be repatriated.
Danish subsidiary Spies said in a press release on Monday that none of its planes will be leaving, and about 1,400 travelers are affected. A press contact in Thomas Cook said that affected travelers will get their trips refunded.
Thomas Cook unit Oy Tjäreborg says it has a total of 2,884 passengers currently traveling. "We are currently doing all we can to arrange return flights for passengers and will provide more information during the day," the company said on its website.
The Swedish unit Ving said the number of Swedish passengers currently away came to 16,956. "We are now working intensely to ensure that all affected travelers are flown home with as little disruption as possible", the company said on its website.
The Russian tour operator subsidiary, Intourist said the bankruptcy of Thomas Cook will have no impact on clients, Russian Executive Director Sergei Tolchin told Interfax.
Thomas Cook holiday airline Condor says it will continue its flight operation despite its parent company's insolvency.
"Condor ... is continuing operations," the German airline said in a statement.
Thomas Cook says there are roughly 140,000 holidaymakers currently traveling with its German units.
As of Monday morning the Netherlands unit of Thomas Cook was still operating.
The Polish unit Neckermann said its financial condition is stable and it continues to operate normally, with holidaymakers unaffected.
A Greek tourism ministry official told Reuters that about 50,000 tourists are stranded.
"The top priority now is to get them back home," the official said, declining to be named.
Spanish Airport operator Aena says 46 flights operated by Thomas Cook have been cancelled in Spanish airports. Between 25,000 and 30,000 tourists are affected in the Canary Islands, according to local media.
The Turkish Ministry of Tourism said it will provide support for local companies affected by the Thomas Cook collapse.
The Hotelier Federation head said about 45,000 tourists from the UK and Europe are in the country.