Gatwick Airport was forced to shut its runway for almost an hour due to a "suspected drone incident".
A Gatwick spokesperson said: "Operations at London Gatwick were suspended temporarily at 1.44pm, while investigations into the sighting of a suspected drone close to the airfield took place.
"These investigations have now completed and the airfield reopened at 2.35pm.
"Twelve inbound aircraft were diverted to other airports during the investigation, however we expect many of these to return to London Gatwick today."
They added that passenger safety was the airport's "absolute priority".
A total of seven easyJet flights to Gatwick were diverted to nearby airports during the disruption.
"We are arranging for onward travel to Gatwick for passengers," a spokesperson told Sky News.
Landings have since resumed at the airport, in Crawley, West Sussex.
Gatwick Airport's runway was shut down for 30 hours in December 2018 due to an incident involving multiple drone sightings.
The airport, Britain's second busiest, said there were more than 100 drone sightings around the site over three days.
The 2018 incident was the first time a major airport in the UK had been shut down due to drones.
The disruption affected more than 140,000 passengers across a total of 1,000 flights.
No one has ever been charged over the incident, which Gatwick insisted was a sophisticated, malicious and well-planned attack.
As a result of the incident, the government introduced new legislation to extend no-fly zones around airports from 0.6miles (1km) to three miles.
Those who recklessly or negligently endanger an aircraft with a drone can face up to five years in jail under UK law.