Thousands of passengers stranded in UK as drones shut Gatwick Airport for 2nd day

Travel plans for thousands of passengers went awry on Thursday ahead of the Christmas holiday period after one of UK's busiest airports remained closed for the second day due to a number of drones spotted near its runway, evoking a stern warning from Prime Minister Theresa May.

The runway of Gatwick Airport, Britain's second-busiest after Heathrow Airport, remains closed since Wednesday night, when two devices were seen flying over the perimeter fence.

After the sighting of another drone on Thursday afternoon, the authorities were unable to reopen the runway "until it was safe to do so".

Prime Minister May described the situation as "irresponsible and completely unacceptable".

"These drones have been flown illegally and the law couldn't be clearer that those found endangering aircraft could face up to five years in jail," her spokesperson said.

"We are in close contact with Gatwick Airport as they work with police to safely resolve the situation as quickly as possible," the spokesperson said.

"Our hearts go out to all those who are desperately trying to go on holiday or arrive in the UK via Gatwick. I know the police are doing all they can to catch the operators of these drones," said House of Commons Leader Andrea Leadsom.

Local Sussex Police investigating the incident at the airport in the south of England have not been inclined to shoot down the devices because of the risk from stray bullets.

The force said it did not believe the drones are terror-related but a "deliberate act" of disruption, describing the devices as of "industrial specification".

"The police are looking for the operator and that is the way to disable the drone," said Gatwick's Chief Operating Officer (COO) Chris Woodroofe.

Around 110,000 passengers on 760 flights were due to fly out on Thursday, as the Christmas holiday period kicks in. The airport authorities warn that the disruption could last "several days".

Incoming planes were diverted to other airports including London Heathrow, Luton, Birmingham, Manchester, Cardiff, Glasgow, Paris and Amsterdam.

Crowds of travellers spent the morning waiting inside Gatwick's terminal for updates, while others reported being stuck on grounded planes for hours.

The UK's Civil Aviation Authority said it considered this event to be an "extraordinary circumstance", and therefore airlines were not obligated to pay any financial compensation to passengers.