Allbury's collapse follows the demise of the Globespan airline
Thousands of overseas holidays have been cancelled after the collapse of a UK travel firm.
Allbury Travel Group, based in Hertfordshire - operating under the brands Libra Holidays, Argo Holidays and JetLife - has ceased trading.
The Civil Aviation Authority said it had moved to protect those customers currently on holiday and arrange to bring them back to Britain.
Nearly 100 holidaymakers are thought to be abroad, in Greece, Cyprus and Egypt.
Along with 4,000 forward bookings, the package holidays should be covered through the ATOL industry insurance scheme.
CAA's advice to Allbury travellers is that they should not go to their departure airport, as all holidays have been cancelled.
Allbury's departure airports were Gatwick, Manchester, Newcastle, Birmingham and Leeds Bradford.
The CAA is making arrangements to ensure customers on Allbury Travel Group holidays remain in their holiday accommodation and fly home as planned.
Hoteliers and company representatives at resorts are being informed, and customers who are currently abroad can call the CAA for more information on 0044 203 441 0846.
The company administrator Begbies Traynor has been appointed to handle the collapse.
On Wednesday another travel company and airline, Globespan and its flyGlobespan subsidiary, went into administration with 4,500 people stranded overseas and 550 workers made redundant so far.
The administrator of that Edinburgh-based company is querying why around £30m was held back from Globespan by E-Clear, the company that handles its credit card transactions.
E-Clear also handled credit card transactions for the Allbury Travel Group.