A Hampshire-based travel agent has collapsed with the loss of 20 jobs.
The independent Davis World Travel shut its four branches after going into liquidation on Wednesday following 53 years of trading.
It is unclear how many holidaymakers are currently abroad but those with Davis World Travel tickets are urged to contact their airlines.
Administrator Begbies Traynor said the company had become "another victim of the recession".
The administrator said customers who had booked a holiday, including packages and flights, should first contact the tour operator or airline directly.
Those who have paid or part paid and have not yet travelled should contact their tour operator in the first instance.
Customers who are abroad with a scheduled flight booked should not be affected but those abroad having travelled on Davis World Travel tickets should, as a precaution, contact their airline to be sure they are covered.
Customers who paid with a credit card will be afforded additional protection.
The travel agent's four branches, in Lee-on-the-Solent, Gosport, Fareham and Portchester, have closed and its website is offline.
Begbies Traynor said the company had a turnover of about £5m to £6m generated through bookings for traditional package holidays as well as city breaks and cruises.
Antony Fanshawe, from Begbies Traynor, said: "Despite its long-standing pedigree, this company has been a victim of a sea change in the way we book holidays.
"Add to this the events of the last year, the recession, volcanic ash, airline strikes and the impending threat of increased air taxes and the result has been devastating for this business.
"This is another business which has fallen prey to global events since the beginning of the recession."
A helpline has been set up and will be available from 1000 GMT on 023 8038 2702.