British Airways has cancelled all flights to the Egyptian capital Cairo for a week as a security "precaution".
Passengers about to board a BA flight to the city from London's Heathrow Airport were told that it was cancelled - and that there would be no alternative flights for a week.
The airline did not specify what the security issue was.
A spokesman for Cairo airport told the BBC the airport had yet to be notified by BA of any such changes.
A BA spokesman said: "We constantly review our security arrangements at all our airports around the world, and have suspended flights to Cairo for seven days as a precaution to allow for further assessment.
"The safety and security of our customers and crew is always our priority, and we would never operate an aircraft unless it was safe to do so."
Christine Shelbourne, 70, from Surrey was due to go to Cairo for a week on Saturday with her 11-year-old grandson. She said she managed to check into the flight at 1500 (1400 GMT). However, her boarding card wouldn't open the barriers.