Thomas Cook could go into the administration this weekend unless the travel company found the £ 200 million in additional funds needed to secure its future.
Banks, including RBS and Lloyds, urge the company to offer new contingency funds in case it needs extra money in the winter months.
The collapse will leave 1
Sources insist there are still "reasonable prospects" for the deal.
But they added that the next 24 hours were crucial to the survival of the tourist group.
There are currently 600,000 Thomas Cook vacation clients out of which 150,000 to 160,000 are from
- Thomas Cook: Answering Your Questions
- What's wrong with Thomas Cook?
The troubled operator hoped to seal a rescue system operated by Chinese Fosun this week. But lender banks issued a last-minute request for the travel company to find an extra £ 200m.
Sources have confirmed that the Civil Aviation Authority is ready with a repatriation plan called Operation Matterhorn. The potential cost of bringing home travelers is around £ 600 million.
The CAA said, "We are in regular contact with all major ATOL owners and are constantly monitoring the company's operations. We do not comment on the financial situation of the individual companies we regulate. "
One woman decision for 8,000 British pounds
Teacher Jackie Cunningham and her partner, train driver Angus McNair of Brentwood, Essex, booked a Maldives vacation with Thomas Cook in December. The luxury journey is to celebrate Mrs. Cunningham's recovery from cancer.
They made a deposit of £ 500 and the balance of £ 8,000 is due by midnight on Friday.
Thomas Cook, of course, still works. But their difficulty underlines the anxiety that many customers are experiencing.
Ms Cunningham and Mr McNair called a customer service line and asked if they could delay the payment of £ 8000 until they realized that the tour operator would not fall into administration. But they were told the deadline remained, or they would lose their deposit of £ 500.
"We were going to pay with a debit card, but now I think we will put it on the credit card if we keep going," Mrs.
"We would like to go on vacation, but we want to know that we will they understand the 200 million pounds they are looking for. "
Thomas Cook has 22,000 staff, 9,000 of those in the UK. It serves 19 million customers annually in 16 different countries.
But Thomas Cook's financial troubles have intensified over the last year, ending with an August settlement deal led by Fosun's largest shareholder, which will see the Chinese firm refinance the 179-year-old British firm.
- Thomas Cook "race to finalize bailout deal"
- Weak pound stimulates British tourism industry
In July, Thomas Cook drafted a business plan saying he needed £ 900m in refinancing compared to a previous estimate of 150m £. 900 million pounds will come from Fosun, the group of creditors and some other investors.
Thereafter, a group of lenders commissioned an independent review. Its financial advisers have said that Thomas Cook will require an additional £ 200m over the already needed £ 900m, bringing the total refinancing needed to £ 1.1bn.
Thomas Cook was able to find an assistant to provide the extra £ 200m, but the BBC understands that the backer has already withdrawn and the creditor group will not return to the table unless additional funding is found.
The final vote on the deal is expected this week, but it is delayed until next Friday, given the latest demand for additional reserve funding.
Earlier this week, Thomas Cook said he was "focused on closing" the deal. He is thought to be in talks with his banks, bondholders and Fosun in an effort to keep the road bailout.
In May, the operator reported a loss of 1.5 billion pounds in the first half of the year. She also issued three profit warnings in the last year and is struggling to reduce her debt.
Blames a series of problems on its profit warnings, including political unrest in holiday destinations such as Turkey, the prolonged heatwave of last summer, and customers delaying holiday reservations due to Brexit.
What are your rights?
If you are on a package holiday, you are covered by the Air Travel Organizer (ATOL) licensing scheme.
The scheme will pay for your accommodation abroad, although you may need to move to another hotel or apartment.
ATOL will also pay to bring you home if the airline no longer operates.
If you have a booked vacation in the future, you will be reimbursed and
If you have booked a flight-only deal, you will need to apply for your travel insurance company or credit card and debit card provider to request a refund.
When Monarch Airlines crashes in 2017, the government organized to bring all affected passengers home, whether or not covered by ATOL.
Here is more information on Atol protection and your questions answered
In addition, it has suffered from competition from online travel agents and low cost airlines.
The winter months can put a strain on the finances of tourism companies, as they typically generate less revenue, while providers have to pay for services provided during the high summer season.