Turkey's tourism establishments cannot request additional payments from Thomas Cook customers, the Turkish Culture and Tourism Ministry announced on Monday.

One of Britain’s biggest holiday operators and airline, Thomas Cook has “ceased trading with immediate effect”, the U.K. Civil Aviation Authority said on Monday morning.

“All Thomas Cook bookings, including flights and holidays have now been cancelled,” the authority said.

Peter Fankhauser, the chief executive of Thomas Cook, said the tour operator’s collapse was a “matter of profound regret”.

He also apologized to the company’s millions of customers, and thousands of employees. It is believed that around 150, 000 people are expected to be affected by the cancelled flights.

“The government is working with the U.K. Civil Aviation Authority (CAA) to help passengers return to the U.K.,” a government statement said.

The group’s four airlines will be grounded and its 12,000 employees in 16 countries as well 9,000 in the U.K., are expected to be losing their jobs, due to insolvency.

The collapse of the iconic 178-year-old British tour operator came, due to financial difficulties and failure to secure a deal of around £1.1 billion ($1.37 billion).

Turkish authorities moved to reassure tourists in Turkey

Hours after the collapse of British tour operator Thomas Cook, Turkish authorities moved to reassure tourists in Turkey who booked and paid for their holidays through the iconic firm.

Turkey's tourism establishments cannot request additional payments from Thomas Cook customers, the Turkish Culture and Tourism Ministry announced on Monday.

The payments of Thomas Cook U.K. guests staying in Turkish tourism establishments -- including for over the weekend -- are guaranteed by the Air Travel Organiser's Licence (ATOL) of the U.K. Civil Aviation Authority (CAA), the ministry tweeted.

It said that as of Monday, there were over 21,000 guests of Thomas Cook U.K. in Turkish accommodation facilities.

If establishments request additional payments from Thomas Cook U.K. guests or vacate them from their rooms, these establishments will face legal action, it added.

The ministry said that it would shortly provide a credit support package with the country's Treasury and Finance Ministry for tourism firms affected by Thomas Cook's collapse.

For canceled flights, the Air Travel Organiser's Licence announced that it is organizing new flights for these passengers.