British Airways flights are disrupted due to a “technical issue”, the airline said.
Flights to and from the UK’s two busiest airports, Heathrow and Gatwick, appear to be among those affected.
A spokeswoman for the airline said: “Our teams are working hard to resolve a technical issue which is affecting some of our flights, and we have re-booked customers onto alternative flights and offered hotel accommodation where they have been unable to continue their journeys last night.
“We are very sorry for the disruption to their travel plans.”
Customers were urged to check ba.com for the latest flight information and ensure their contact details are up to date on their booking.
It is the latest in a series of systems failures suffered by the airline in recent months.
In August, an IT glitch caused the cancellation of more than 100 flights and disrupted the travel plans of tens of thousands of passengers.