Passengers at one of the UK's busiest airports have been warned to expect further flight disruption after drones were seen over the airfield.

Gatwick's runway remains closed after two of the devices were seen nearby, sparking a string of delays and diversions on Wednesday evening.

Outbound flights were grounded and incoming planes redirected - with some landing in Paris and Amsterdam.

Passengers due to travel have been told to check the status of their flight.

The shutdown started just after 21:00 GMT, when two drones were spotted being flown over the airfield.

"Multiple reports" of further sightings followed, a Gatwick spokesman said, and all flights to and from the airport were suspended.

The runway was briefly reopened at about 03:01, the airport said, but forced to close again about 45 minutes later amid "a further sighting of drones".

'Significant disruption'
Chris Woodroofe, the airport's chief operating officer, told the BBC the runway would remain closed until at least 08:00 as staff tried to find a drone which had been reported as still being in the air.

He said about 2,000 flights had been unable to take off - affecting 10,000 passengers - after the two drones had been seen flying "over the perimeter fence and into where the runway operates from".

Mr Woodroofe said the drones had sparked "very significant disruption for passengers" but that police did not want to shoot them down because of the risk from stray bullets.

He added that 20 police units from two forces were hunting for the drone operator.

It is illegal to fly a drone within 1km of an airport or airfield boundary.

Planes were diverted to other airports including London Heathrow, Luton and Manchester.

Aviation website airlive.net said some services were re-routed as far away as Cardiff, Paris and Amsterdam.

Crowds of passengers waited inside Gatwick's terminal for updates, while others reported being stuck on waiting planes for several hours.

Kasia Jaworska told the BBC she had been travelling from Glasgow to Gatwick with her boyfriend when her flight was diverted to Luton.

After spending about two hours on the plane, she said the couple were put on a bus to Gatwick, from where they had been due to fly to Istanbul.

Ms Jaworska said she thought it was "strange" that two drones had led to the closure of the airport.

"You would imagine there would be better security in place and emergency action for something like that," she added.

Christopher Lister, who had been returning from Kiev, posted a picture of people sleeping "on every seat and across the floors" on board his flight.

He said the photo was taken six hours after the plane - which was due to arrive at Gatwick - landed in Birmingham.

Luke McComiskie, whose flight ended up in Manchester, described chaotic scenes as people tried to find their way home after more than three hours stuck onboard.

The 20-year-old, from Aldershot, told the Press Association: "We got told there would be some arrangements with coaches for us when we get out the terminal.

"It was just chaos and they had only two coaches and taxis charging people £600 to get to Gatwick."

Eddie Boyes said he and his family had been at the airport for six hours and people were sleeping on the floor.

Drones and airports

The law says:

It is illegal to fly a drone within 1km of an airport or airfield boundary
Flying above 400ft (120m) - which increases the risk of a collision with a manned aircraft - is also illegal
Endangering the safety of an aircraft is a criminal offence which can carry a prison sentence of five years

Source: dronesafe.uk

Gatwick Airport said airlines were "working to provide affected passengers with hotel accommodation" or provide alternative travel options.

A spokesman apologised for any inconvenience and said staff were working alongside Sussex Police to investigate the drone sightings.

British Airways said a "very small number of flights" had been diverted.

According to its website, the airport expects to welcome a "record-breaking" number of passengers over this year's Christmas period.

It predicts 2.9m people will pass through its gates during the festive getaway, with 73,000 of those due to depart this Sunday.