All flights have resumed at Heathrow Airport in London after earlier reports of a drone sighting.
The airport said it was working with police to prevent any threat to operational safety.
One of its two runways was closed and all departures were stopped as a precautionary measure while an investigation took place.
In a tweet, the airport has apologised to passengers for the inconvenience.
We are responding to a drone sighting at Heathrow and are working closely with the Met Police to prevent any threat to operational safety. As a precautionary measure, we have stopped departures while we investigate. We apologise to passengers for any inconvenience this may cause.
— Heathrow Airport (@HeathrowAirport) January 8, 2019
It's not known if a drone was found.
There was massive disruption at nearby Gatwick Airport in the run up to Christmas, after a number of drone sightings saw thousands of flights cancelled.