Flights in and out of Gatwick have been suspended after air traffic controllers received reports of two drones flying close to the airport.
The airport said it was investigating the incident and apologised to customers for the inconvenience.
A statement said: “Following reports of two drones flying over the Gatwick Airport airfield, we have had to suspend flights while this is investigated.
“We apologise to any affected passengers for this inconvenience but the safety is our foremost priority.”
Several passengers reported long waits for take off or diversions.
Twitter user Seun Olayanju posted: “@AerLingus currently stuck at Gatwick waiting for the heavily delayed E10249 to Dublin. Please can you confirm if the flight will run tonight?”
Honor Ireland wrote: “Landed at Stansted when we should be at @Gatwick_Airport due to a supposed drone sighting – car is at Gatwick, fantastic! #gatwickairport”
John Belo said: “Plane should have departed an hour ago from @Gatwick_Airport – captain confirmed there are reports of a drone in the area … still waiting.”