One of the biggest emergency airlifts of modern history was under way yesterday as the Civil Aviation Authority sought to help 85,000 holidaymakers stranded at resorts across the world by the collapse of XL Leisure.

CAA staff were working frantically to charter jets from XL's commercial rivals to collect passengers from summer "sea and sand" destinations in the Mediterranean, southern US and the Caribbean.

All 50,000 people who booked a package holiday with XL and the 25,000 people who booked through them but are travelling with other tour operators should receive free flights home. But a further 10,000 people who booked a flight only with the UK's third biggest tour airline are not protected by the industry's protection scheme, Atol, and will have to make their own way home. Many will have to pay hundreds of pounds for a flight.

Even those who are protected may have to wait for days after their departure date before being flown back, amid scepticism that the CAA will be able to rescue all the stranded passengers on time.

It also emerged yesterday that the Government could be forced to top up the CAA's compensation scheme, at a cost of £20m to the taxpayer. The authority is able to claim £42m from seven of the UK's largest insurers, but the total cost of XL's failure is about £60m, leaving a £20m shortfall.

Future holidays with XL booked by a further 200,000 people will be cancelled. Those who booked by credit card will be able to get refunds, as will those who booked through a bonded travel agent, but flight-only customers who paid by cash, cheque or some debit cards may lose out. The CAA said that Virgin, BA, Thomas Cook and Thomson airlines had offered assistance to try to bring back holidaymakers stranded in 40 locations across the globe, mostly in resorts in Greece, Spain, Turkey and Egypt, but also in the US, Barbados, Tobago, St Kitts – and even Zimbabwe.

Consular officials were providing "advice and information" to those stranded, but there were reports of passengers sleeping in airports after having had their flights home cancelled.

Debbie Taylor, on a break in Portugal with her husband and son, said they had heard "absolutely nothing" from their tour operator and only learnt of its collapse when she turned on the television. "I don't think we're going to really enjoy it now because we've got to spend the whole day trying to sort out how we're going to get home next week," she said.

As the rescue operation got under way, details emerged of XL's chaotic final hours. At Orlando airport, passengers were hauled off a plane which had been heading towards the runway. "The passengers were on the plane and it had pushed from the gate," said Diane Crews, a spokeswoman for Florida's Orlando-Sanford airport. "But the company got in contact with the tower and the aircraft had to return to the gate." About 100 people were forced to bed down in the airport on Thursday night.

Most of XL's staff learnt from the media reports that they were losing their jobs after a 2am meeting with the administrators, Kroll, failed to stave off the collapse. Some were on duty on aircraft when they heard the news.

The first stranded holidaymakers were due to arrive at Gatwick yesterday on a chartered BMI flight from Minorca.

David Clover, a spokesman for Atol, said: "With XL Airways no longer operating, we are bringing in substitute aircraft to take people home. We ask people to be patient while we organise that ... Our priority is the stranded passengers abroad and getting them back to the UK. If people do incur some additional costs, if they are delayed in their return, then they can put a claim in to the CAA under the Atol scheme."

Virgin Atlantic said XL passengers stuck at airports in Florida and the Caribbean would be offered special one-way fares of $349 (about £195) to fly home. The deal also covers flights to Gatwick from Barbados, Antigua, St Lucia, Grenada, Tobago and Jamaica, as well as flights from St Lucia and Barbados to Manchester. Ryanair offered the CAA the use of one of its spare Boeing 737-800 aircraft for the next fortnight, while BA said it would extend special one-way fares to XL customers from Florida, the Caribbean, Israel, Egypt and all European destinations.

XL's chief executive, Phil Wyatt, said he was "devastated" and apologised to customers and employees. "It's going to be the most challenging airlift, I believe, that anyone has undertaken," he said.

Passengers turning up at airports across Britain discovered that they would not be able to go on holiday. Tom Penman, 42, from Douglas in Lanarkshire, Scotland, said: "It's shocking. We've saved up for two years and now the children are in tears. We didn't go on holiday last year to save up for this one. Now we're scrambling for tickets and we are stuck."

Historic rescues

*The Spanish AirLift

The world's first successful

airlift took place in July 1936 when the Luftwaffe transported 20,000 troops and equipment for Franco from Spanish Morocco to fight the Republican government in Spain.

*The Berlin AirLift

American, British and French aircraft kept Berlin supplied with food and fuel between June 1948 and May 1949 to break a Russian blockade.

*Desert Shield Airlift

Gulf War 1991: Three quarters of the cargo and a third of the personnel were delivered by air. A pilot said: "You could have walked across the Med on the wings of C-5s, C-141s, and the aircraft moving across the region."