A number of flights into Gatwick Airport have been diverted after reports of a drone flying close to the runway.
A spokesman for the airport said that a "handful" of planes were sent to other airports and several more had to circle during the alert.
EasyJet said four of its flights were diverted away from the airport to London Southend.
British Airways was also forced to divert one of its planes from Valencia to Bournemouth Airport, which is expected to take off again shortly, a spokesman said.
Among those delayed and venting their frustration on Twitter was Holly Johnson, formerly the front man of British band Frankie Goes To Hollywood.
A Gatwick Airport spokesman said operations had since returned to normal but there were delays as a knock-on.
They said the sighting was still unconfirmed.