London's Gatwick Airport has reopened after a drone saboteur wrought travel chaos for hundreds of thousands of Christmas travellers by flying drones overhead, playing cat-and-mouse with police snipers and the army.

Key points: Aviation experts fear the drone disruptions could encourage copycats

Aviation experts fear the drone disruptions could encourage copycats Police said there was nothing to suggest the sabotage was terror-related

Police said there was nothing to suggest the sabotage was terror-related Anyone caught flying a drone within 1 kilometre of a British airport could be jailed for up to five years

Following the biggest disruption at Britain's second-busiest airport since a volcanic ash cloud in 2010, Gatwick said its runway was open and that 700 planes were due to take off on Friday (local time), although there would still be delays and cancellations.

The army and police snipers were called in to hunt down the drones, thought to be industrial-style craft, which flew near the airport every time it tried to reopen on Thursday.

A police helicopter flies over the airport's runway. ( AP: Pete Summers )

There was mystery over the motivation of the drone operator, or operators, and police said there was nothing to suggest the crippling of one of Europe's busiest airports for 36 hours was a terrorist attack.

Police Detective Chief Superintendent Jason Tingley said that "our assessment, based upon the information that we have available to us, is that this incident is not terrorism-related".

Gatwick's chief operating officer Chris Woodroofe said the perpetrator had not been found, but that additional security measures had given him the confidence to reopen the airport.

Loading

Loading

Flights were halted on Wednesday night after two drones were spotted near the airfield.

The disruption affected 120,000 people and caused misery for tens of thousands of travellers who were stranded at Gatwick.

Many slept on the floor as they searched for alternative routes to holidays and Christmas family gatherings.

Transport minister Chris Grayling lifted night-flying restrictions at other airports to ease congestion caused by diverted aircraft.

Stranded passengers have been left with nothing to do but wait until officials reopen the runway. ( AP: Tim Ireland )

After a boom in drone sales, unmanned aerial vehicles have become a growing menace at airports across the world.

In Britain, the number of near-misses between private drones and aircraft more than tripled between 2015 and 2017, with 92 incidents recorded last year.

Flying drones within 1 kilometre of a British airport boundary is punishable by five years in prison.

Experts fear copycat incidents

Richard Parker, head of the air traffic management technology firm Altitude Angel, said this was the first time a major airport had been hit by such a sustained and deliberate incursion into its airspace.

"It's sophisticated — not from a technology side, but it's organised," he said.

"People have charged lots of batteries, and are deliberately trying to avoid being caught, probably by driving around to different locations.

"It really is unprecedented."

Drone expert Peter Lee of Portsmouth University said with the introduction of cheap, commercially-available drone technology, he and others had been anticipating this kind of disruption.

"You can achieve a high amount of disruption for a very, very low cost," he said.

"One of my concerns about today is that it may well encourage copycat incidents."

Reuters