British Airways has suspended all flights to Cairo for seven days as a security precaution.
The airline announced on Saturday evening that all flights into the Egyptian capital were halted.
A statement 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.”
Some affected passengers used social media to share pictures which appeared to show a letter handed out by British Airways with a similar message about security.
A spokeswoman for the airline said it could not immediately offer more information about the suspensions.