Thomas Cook has ceased trading following the collapse of recuse talks aimed at saving the 178-year-old company.
All the organisations in the group will cease operations from today, including Thomas Cook Airlines.
Hundreds of retail shops will also be closed.
Despite agreement on a potential deal to save the company earlier this month, a last minute demand for up to £200 million in further liquidity pushed the tour operator over the edge.
Peter Fankhauser, chief executive of Thomas Cook, commented: “We have worked exhaustively in the past few days to resolve the outstanding issues on an agreement to secure Thomas Cook’s future for its employees, customers and suppliers.
“Although a deal had been largely agreed, an additional facility requested in the last few days of negotiations presented a challenge that ultimately proved insurmountable.”
Following the collapse, the British government and Civil Aviation Authority are working together to fly as many as 150,000 customers who are currently overseas back to the UK.
Some 16,000 holidaymakers are booked to come back on Monday.
Authorities hope to get at least 14,000 of them home on chartered flights.
The government has chartered 45 jets to bring customers home and they will fly 64 routes today.
The size of the fleet will make it temporarily the fifth largest airline in the UK.
Operators including easyJet and Virgin have supplied some aircraft, with jets coming from as far afield as Malaysia.
Fankhauser added: “It is a matter of profound regret to me and the rest of the board that we were not successful.
“I would like to apologise to our millions of customers, and thousands of employees, suppliers and partners who have supported us for many years.
“Despite huge uncertainty over recent weeks, our teams continued to put customers first, showing why Thomas Cook is one of the best-loved brands in travel.
“This marks a deeply sad day for the company which pioneered package holidays and made travel possible for millions of people around the world.”
The failure puts 22,000 jobs at risk worldwide, including 9,000 in the UK.
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