Thomas Cook will hold crisis talks in a final bid to secure a rescue agreement.
The meeting with its largest shareholder and creditors is understood as scheduled for Sunday morning at the city's law firm Slaughter & May.
The tour operator can fall into administration over days unless it finds £ 200m in extra funds. [1
The government has been called in to bail the company amid fears that the collapse could leave around 150,000 British tourists stranded.
Concerned customers have been reminded on social media that they have Atol protection – a kind of industry-supported insurance – "in case Thomas Cook goes into administration".
The travel company has also reassured customers on Saturday night that flights continue to function normally.
& # 39; Held as hostage & # 39;
Guests at Les Oranger's beach resort in Hammamet, near Tunis, said the hotel refuses to let them leave because of concerns about Thomas Cook's future.
Customers have reported that the hotel is asking visitors to pay extra in the midst of fear that it will not be paid what it is due to the booking operator for bookings.  Ryan Farmer, from Leicestershire, told BBC Radio 5 Live that the hotel required all guests to leave to reception "to pay extra fees, obviously due to the situation with Thomas Cook."
Security guards closed the hotel's gates as guests refused to pay the surcharge, Farmer claims.
He told the Stephen Nolan show: "I would describe it as exactly the same as being held hostage."
The Federated Transport Salaried Staffs Association (TSSA), which represents employees of the struggling travel company, has called on business secretary Andrea Leadsom to rescue Thomas Cook "no matter what".
Government sources suggest that ministers are reluctant to help the firm.
TSSA Secretary General Manuel Cortes told Leadsom that it was up to the government to save thousands of jobs and to allow Thomas Cook to "flourish".
Shadow Secretary Rebecca Long-Bailey said "all viable options" to save the travel giant should be explored.
She added that "the government must consider stepping in and taking a stake to avoid this crisis."
BBC business editor Simon Jack reported on Saturday that government sources had questioned the economic wisdom by going in to save the company.
He said the government did not see it We are between spending £ 200 million to help Thomas Cook with cash shortages or £ 600 million to repatriate his UK customers abroad.
Currently there are 600,000 Thomas Cook customers on holiday, 150,000 to 160,000 of whom are British.
One of the world's largest travel companies, Thomas Cook was founded in 1841 to conduct temperance day trips, and now has a turnover of £ 9 billion.
It employs 22,000 employees, 9,000 of whom are in the United Kingdom, serving 19 million customers a year in 16 different countries.
Chloe Hardy from Leicestershire is due to get married in Zante in October and booked the wedding package with Thomas Cook back in June 2018.
Chloe and the fiance will also have 33 family members flying out, with their trips costing more than £ 33,000 in total .
As the big day looms, Chloe is frustrated with Thomas Cook's handling of the booking.
"I have e-mailed the wedding concierge and coordinator and none of them have come back to me. We are unsure if we will be able to fly. Although it is Atoll protected, I have booked three weeks' leave from work and there is no guarantee that I will be able to get free if I have to rebook. "
" We have had constant questions from our family that we cannot answer, "she added. "This causes great concern, worry and stress for all of us involved."
Thomas Cook's financial difficulties have grown over the past year, culminating with the August agreement on a rescue agreement led by its largest shareholder Fosun.
In July, Thomas Cook produced a business plan that said it needed £ 900m in refinancing, up from a previous estimate of £ 150m. £ 900 million would come from Fosun, the group of creditors and some other investors.
The group of lenders then ordered an independent inquiry. Its financial advisers said Thomas Cook would demand an additional £ 200 million on top of the already needed £ 900 million, which would provide the total refinancing needed up to £ 1.1 billion.
Thomas Cook succeeded in finding a supporter to give the extra £ 200m, but the BBC understands it has since pulled out.
The company has blamed a number of problems for the profit forecasts, including political turmoil in holiday destinations such as Turkey, last summer's extended heat wave and customers who delayed booking holidays due to Brexit.
What are your rights?
If you are on a package tour, you will be covered by the Air Travel Organizer's License Scheme (Atol).
The scheme will pay for accommodation abroad, although you may need to move to another hotel or apartment.
Atol also pays to take you home if the airline is no longer operating.
If you have a holiday booked in the future, you will also be reimbursed.  If you have booked an airline ticket, you must seek your travel insurance company or credit and debit card provider for a refund.
When Monarch Airlines collapsed in 2017, the government organized to bring home all the stranded passengers, whether covered by Atol or not.
Here is more information about Atol protection and your questions answered
Are you a Thomas Cook customer or employee? If you have been affected by the issues raised here, please contact us by emailing.
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