The foreign secretary has insisted Thomas Cook passengers will not be stranded overseas if the company collapses into administration.
Dominic Raab’s reassurances came as the embattled travel group met shareholders and creditors on Sunday morning in a final attempt to piece together a rescue deal.
The 178-year-old company needs to secure a £200m lifeline following a demand from lenders – or face being placed into bankruptcy proceedings in the early hours of Monday.
Such a move would trigger Britain’s biggest-ever peacetime repatriation operation, as 165,000 holidaymakers will need to be flown back to the UK.
Speaking to the BBC, Mr Raab said: “We have got all the contingency planning to make sure no one will be stranded.
“I don’t want to give all the details of it because it depends on the nature of how people are out there, whether they have got a package holiday or whether they just paid for the flights and sorted out something separately.”
He added: “But I can reassure people that in the worst case scenario, the contingency planning is there to avoid people being stranded.”
Britons who are currently on holiday with Thomas Cook – as well as those who are about to travel – have faced a nervous wait as the business tries to avert collapsing into insolvency.
Guests at the Les Orangers beach resort in the town of Hammamet in Tunisia said their hotel was refusing to let guests leave while demanding extra money on Saturday.
Ryan Farmer, from Leicestershire, told BBC Radio 5 the hotel had summoned all guests who were due to leave to go to reception “to pay additional fees, obviously because of the situation with Thomas Cook”.
With many tourists refusing to pay on the grounds they had already paid Thomas Cook, security guards were said to be keeping the hotel’s gates shut, refusing to allow guests out, or to let new visitors enter.
Mr Farmer said: “We can’t leave the hotel. I’d describe it as exactly the same as being held hostage.”
On Saturday, a British woman in Majorca told Sky News she was afraid she would run out of heart medication if her return flight was cancelled because of the operator’s financial strife.
Jackie Ward, 58, and her daughter Amy, 24, from Newcastle, arrived there in the last week for a celebratory holiday after Jackie was given the all-clear from cancer.
A stranger who heard of Jackie’s plight in a Sky News interview subsequently booked and paid for flights home regardless of the airline’s outcome – meaning they “can relax and enjoy what’s left of the trip”.
Thomas Cook reassured worried customers on Saturday night that their flights continue to operate as normal and all their package holidays are ATOL-protected.
With 20,000 jobs across the group at risk, including 9,000 in the UK, the Transport Salaried Staffs’ Association, which represents workers at the company, said ministers should be ready to offer “real financial support”.
The association’s general secretary Manuel Cortes called for an urgent meeting with Business Secretary Andrea Leadsom.
He said in a letter: “It is incumbent upon the government to act if required and save this iconic cornerstone of the British high street and the thousands of jobs that go with it.”
Shadow business secretary Rebecca Long Bailey said: “The government faces a simple choice between a £200 million government cash injection to save the company now versus a £600 million bill to repatriate UK holidaymakers.”
More than 3000 of the UK job losses would be in Greater Manchester.
The city’s mayor Andy Burnham tweeted on Sunday: “I’m hearing today is make-or-break for @ThomasCookUK, its customers and the 3000+ people working for them in Greater Manchester.
“Situation is rescuable but much more likely with government support.
“About to write to @10DowningStreet asking for an urgent intervention.”
The Civil Aviation Authority is spearheading plans for the repatriation operation should it be needed, and the exercise has been code-named Project Matterhorn.
In recent days, the London-listed company has explored a multitude of options to raise the remaining £200m required by its banking syndicate.
Many of those have been discounted because there is insufficient time to implement them before Thomas Cook runs out of money.
A plan for Triton Partners to buy Thomas Cook’s Nordic operations was still under discussion on Saturday, as was a proposal to keep its airlines in the UK, Germany and northern Europe out of administration while letting its British tour operating arm fail.
However, one insider suggested that neither was likely to be viable.
A request for emergency government funding was made by Thomas Cook earlier this week, with executives arguing that the cost to taxpayers would be dwarfed by the bill incurred by the repatriation.
One insider described the widely reported £600m tab, however, as being “a gross overestimate of the cost to taxpayers”.
A government spokesman said: “We recognise it’s a worrying time for holidaymakers and employees.
“The financial circumstances of individual businesses are a commercial matter, but the government and the Civil Aviation Authority are monitoring the situation closely.”
Current trading at Thomas Cook is understood to have remained difficult for months, with the ongoing political crisis in Westminster contributing to soft consumer demand for autumn and winter bookings.
On Friday shares in Thomas Cook closed at 3.45p, more than 95% lower than at the same point last year.
The British company was founded in 1841 by a 32-year-old cabinet-maker and former Baptist preacher who began offering one-day rail excursions from Leicester to Loughborough for a shilling.
From there, it went on to become one of the world’s largest holiday companies, marking its 175th anniversary three years ago.
A stranger has paid for a British woman on holiday in Majorca to fly home after hearing she would run out of heart medication if her return flight with Thomas Cook was cancelled amid the operator’s financial strife. The man, named only as Colin, stepped in after he heard of Jackie Ward’s plight in a Sky News interview from her holiday resort.