GATWICK • London's Gatwick Airport reopened yesterday after a saboteur wrought 36 hours of travel chaos for over a hundred thousand Christmas travellers by using a drone to play cat-and-mouse with police snipers and the army.

After the biggest disruption at Britain's second busiest airport since a volcanic ash cloud in 2010, Gatwick said 700 planes were due to take off yesterday, although there would still be delays and cancellations.

Britain deployed unidentified military technology to guard the airport against what Transport Secretary Chris Grayling said were thought to be several drones.

"I think passengers are safe," Mr Grayling said. "Clearly, there are military systems that can help, but we're going to have to work together with all the airports to make sure that we've got systems that give them comfort that planes can fly," he said.

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 was a terrorist attack.

Gatwick's drone nightmare is thought to be the most disruptive yet at a major airport and indicates a new vulnerability that will be scrutinised by security forces and airport operators across the world.

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.

The perpetrator has not yet been detained, police said, and no group has claimed responsibility. British officials were to meet yesterday to discuss the situation. The defence ministry refused to comment on what technology was deployed.

Flights were halted on Wednesday after two drones were spotted near the airfield. The disruption affected at least 120,000 people.

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 1km of a British airport boundary is punishable by five years in prison.

The latest drone sightings caused misery for tens of thousands of travellers who were stranded at Gatwick, many sleeping on the floor as they searched for alternative routes to holidays and Christmas family gatherings.

"There's no evidence that it is terror-related in the conventional sense," Mr Grayling said. "But it's clearly a kind of disruptive activity that we've not seen before. This kind of incident is unprecedented anywhere in the world."

He said it was uncertain how many drones were involved but it appeared to be more than one.

It was not immediately clear what the financial impact would be on the main airlines operating from Gatwick including easyJet, British Airways and Norwegian.

"We are making every effort to get people to their destination at this important time of the year," easyJet said. "We are working to get our operations at Gatwick back to normal, but with runway movements restricted to a limited number per hour, we expect some disruption to continue."

Britain's Civil Aviation Authority said the event was an "extraordinary circumstance", meaning airlines are not obliged to pay compensation to affected passengers.

Airlines will have to refund customers who no longer wish to travel, however, and try to reschedule flights to get passengers to their destinations.

REUTERS