The collapse of the world's oldest travel firm, Thomas Cook, has left thousands of holidaymakers stranded around the globe and sparked the largest peacetime repatriation effort in British history.

Key points: The firm currently has 600,000 people abroad, forcing a huge rescue operation

The firm currently has 600,000 people abroad, forcing a huge rescue operation More than 20,000 jobs are at risk

More than 20,000 jobs are at risk The British Government and the aviation regulator have drawn up a plan to use other companies and airlines to bring Britons home.

The firm runs hotels, resorts, airlines and cruises for 19 million people a year in 16 countries.

It currently has 600,000 people abroad, forcing governments and insurance companies to coordinate a huge rescue operation.

The UK's Civil Aviation Authority said Thomas Cook had now ceased trading and would work with the Government to bring the more than 150,000 British customers home over the next two weeks.

Most of Thomas Cook's British customers are protected by the government-run travel insurance program, which makes sure holidaymakers can get home if a British-based tour operator goes under while they are abroad.

Hurt by high levels of debt, online competition and geopolitical uncertainty, Thomas Cook needed to find 200 million pounds ($368.6 million) on top of a 900 million pound package it had already agreed to see it through the winter months when it needs to pay hotels for their summer services.

More than 20,000 jobs are at risk.

The Transport Salaried Staffs Association, which represents Thomas Cook staff, had appealed to the Government to step in with "real financial support".

Challenge 'proved insurmountable'

Mr Fankhauser said the collapse was a "matter of profound regret" for him. ( Supplied: Thomas Cook )

Peter Fankhauser, the chief executive of Thomas Cook, issued a statement apologising for the company's collapse.

"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," he said.

"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.

"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."

Thomas Cook has ceased trading and is working to bring than 150,000 British customers home. ( Reuters: Luke MacGregor )

The government and aviation regulator said that due to the scale of the situation some disruption was inevitable.

"Thomas Cook has ceased trading so all Thomas Cook flights are now cancelled," the CAA said.

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The demise of Thomas Cook marks the end of one of Britain's oldest companies.

Thomas Cook was started in 1841, running local rail excursions. It survived two world wars and went on to pioneer package holidays, first in Europe and then further afield.

The corporate collapse has the potential to spark chaotic scenes around the world, with holidaymakers stuck in hotels that have not been paid for in locations as far afield as Goa, Gambia and Greece.

In the longer term it could also hit the economies of its biggest destinations, such as Spain and Turkey, leave fuel suppliers out of pocket, and force the closure of its hundreds of travel agents across British high streets.

The British Government and the aviation regulator have drawn up a plan to use other companies and airlines to bring Britons home.

The company has not operated in Australia for almost two decades.

'Like being held hostage'

A British tourist told BBC radio on Sunday that the Les Orangers beach resort in the Tunisian town of Hammamet, near Tunis, demanded guests who were about to leave pay extra money for fear it would not be paid what it was owed by Thomas Cook.

Ryan Farmer, of Leicestershire, said many tourists refused the demand, since they had already paid Thomas Cook, so security guards shut the hotel's gates and "were not allowing anyone to leave".

It was like "being held hostage," said Mr Farmer. He said he would also refuse to pay if the hotel asked him.

Customers have taken to Twitter to vent their frustration and sadness about the company's collapse.

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