Thomson and Falcon Holidays owner TUI has revealed that the terrorist massacre in Tunisia and the Greek debt crisis would have a £20 million impact on earnings.
The attack in June claimed the lives of 38 holidaymakers including three Irish people and 30 from Britain
Tourists were flown home from the North African country and travel operators have cancelled holidays there, with the British Foreign Office and other governments still advising against visits.
The costs of the flights home plus cancellations and switching people booked on holidays to Tunisia to different destinations resulted in an impact of around £20 million on TUI.
It set out details in a trading update for the third quarter to the end of June.
TUI's joint chief executives Friedrich Joussen and Peter Long said: "This quarter was marked by the tragic events in Tunisia at the end of June.
"Supporting our customers, their families and our colleagues through this sad time remains our highest priority.
"We are very proud of the commitment and dedication our colleagues have shown throughout this unprecedented situation."
TUI also said that bookings to Greece in late June and the first half of July were hit by economic uncertainty - as the indebted country neared economic collapse before reaching a deal on a new bailout with creditors.
The company did not give an update on the future impact of the Tunisian atrocity - in a country which has in the past represented 3% of its annual tour operator programmes.
The figures come after rival Thomas Cook revealed a £25 million hit to earnings from events in Tunisia and Greece.