The world’s oldest travel company, Thomas Cook, today went into compulsory liquidation, effectively stranding 600,000 travellers across the planet.

Along with future holiday and wedding plans being cancelled for tens of thousands travellers, tourists currently travelling under Thomas Cook bookings are in jeopardy.

In Tunisia, travellers were barricaded inside a resort over fears the travel firm will be unable to pay bills. More similar stories are expected as the news sinks in.

The firm had run hotels, resorts, airlines and cruises for 19 million people a year in 16 countries. Its Australian operations were disbanded earlier this year.

The move has effectively created one of the worst travel bankruptcies in the history of the industry, with 150,000 travellers affected.  It was not clear whether cruises booked through the company were affected or whether large number of Australians are involved.

The UK Civil Aviation Authority confirmed yesterday the tour operator, one of the oldest and largest in the world, had “ceased trading with immediate effect”.

As such, an emergency operation codenamed Operation Matterhorn will aim to bring home about 150,000 British holiday-makers who have been left stranded overseas –  believed to be the biggest peacetime repatriation operation in British history.

Thomas Cook’s CEO Peter Fankhauser said it was a “deeply sad day” and apologised “to millions” after the cash-strapped travel company went under.

Some 550,000 non-British holiday-makers have been left high and dry with the company’s sudden collapse.

“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,” Mr Fankhauser also stated.

“Generations of customers entrusted their family holiday to Thomas Cook because our people kept our customers at the heart of the business and maintained our founder’s spirit of innovation.

“This marks a deeply sad day for the company which pioneered package holidays and made travel possible for millions of people around the world.”

Thomas Cook, which at 179 years old is one of the world’s oldest travel providers, serves about 19 million customers a year in 16 countries and employs about 22,000 staff worldwide.

Its recent financial strife has been attributed to tough online competition, the high price of jet fuel and concerns over Brexit.

Chinese firm Fosun had agreed to backing a $1.6 billion refinancing but Thomas Cook’s banks ordered it to cough up an extra $368 million as a contingency to see it through winter. It was unable to secure the extra funds before a deadline today.

In a statement, Thomas Cook said discussions over the weekend to secure final terms of recapitalisation had failed and the company’s board “concluded that it had no choice but to take steps to enter into compulsory liquidation with immediate effect”.

Until today, Thomas Cook operated a fleet of close to 100 aircraft, as well as arranging holiday packages — including destination weddings, which are now in limbo.

Thomas Cook customers staying at the Les Orangers hotel in Tunisia said they had been locked inside until they paid 6000 Tunisian dinars, about $A3097, to catch their flights home.

“We’re being held hostage,” British tourist Ryan Farmer told the BBC.

He said guests due to leave were being told to go to reception to pay “additional fees, obviously because of the situation with Thomas Cook”.

“We’ve been up to the gates. They had four security guards on the gates, holding the gates closed, and were not allowing anybody to leave,” he said.

Another British tourist, Chris Rutherford, said the hotel reception “told us we need to pay £4000 ($A7372) to be allowed to leave”.

The British Embassy has reportedly spoken to the hotel.

Under the emergency operation Matterhorn, Empty aircraft have already begun flying overseas to bring Thomas Cook customers home.

In terms of Thomas Cook Cruise Lines, this is the official website message now being distributed on behalf of Thomas Cook.

“Thomas Cook UK Plc and associated UK entities have entered Compulsory Liquidation and are now under the control of the Official Receiver. The UK business has ceased trading with immediate effect and all future flights and holidays are cancelled. A dedicated support service is being provided by The Civil Aviation Authority to assist customers currently overseas and those in the UK with future bookings. Please visit: thomascook.caa.co.uk for further information.”