Tour operator Thomas Cook has hired security guards for its headquarters, it has been claimed.
Security were also brought into its headquarters in Peterborough, Cambridgeshire, and the hubs at Birmingham, Bristol and East Midlands airports, according to Daily Star.
The troubled travel giant will hold talks with key players on Sunday morning in a final bid to piece together a rescue deal.
The move comes as holidaymakers at a hotel in Tunisia report being locked in by security guards as the hotel demands extra money in fear it won't be paid by Thomas Cook.
Sunday's crisis meeting, first reported by Sky News, is understood to be taking place at City law firm Slaughter & May.
Among those attending will be the firm's biggest shareholder along with creditors.
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The travel company is at risk of falling into administration within days unless it finds £200 million in extra funds.
A collapse would leave up to 150,000 UK holidaymakers stranded and the Government is being urged to step in to help save the business.
Thomas Cook continued to reassure worried customers on Saturday night that their flights continue to operate as normal and all their package holidays are ATOL-protected.
However, tourists at the Les Orangers beach resort in the town of Hammamet, near Tunis, say their hotel is refusing to let guests leave while demanding extra money.
A rep in Spain for Thomas Cook told The Sun: "Passengers are panicking."
Ryan Farmer, from Leicestershire, told BBC Radio Five's Stephen Nolan show the hotel had on Saturday afternoon 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 pay on the grounds they had already paid Thomas Cook, security guards were keeping the hotel's gates shut, refusing to allow guests out, or to let new visitors enter.
"We can't leave the hotel. I'd describe it as exactly the same as being held hostage," Mr Farmer said.
The Transport Salaried Staffs Association, which represents workers at the company, said the Government should be ready to assist with "real financial support".
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.
"Thomas Cook can be a highly successful business and must be given every opportunity to flourish. I urge you to stand ready to assist Thomas Cook with real financial support.
"The company must be rescued no matter what. No British government in its right mind would countenance the loss of so many jobs and the prospect of just one major travel operator - TUI - controlling the mass market."
Shadow business secretary Rebecca Long Bailey said: "This is yet more evidence of this Government's indifference to British jobs and businesses going under.
"All viable options must be explored by Thomas Cook and the Government must consider stepping in and taking an equity stake to avoid this crisis.
"Refusing to do so is ideological shortsightedness: 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."
It is understood that Thomas Cook has approached the Government in an attempt to plug a gap in its funding.
