Thousands of passengers at Gatwick, one of the UK’s busiest airports and gateway for many Australians returning home for Christmas, have faced severe flight disruption after drones were spotted over the airfield.

The airport near London shut its only runway on Wednesday evening after two drones were seen flying nearby. It reopened briefly at about 3am UK time (2pm AEDT) on Thursday, but was forced to close again less than an hour later when a drone returned.

Chris Woodroofe, Gatwick’s chief operating officer, told BBC radio that 20 police units from two local forces were looking for the drone operator whose activity was forcing flights to divert to other UK airports as well as to Paris and Amsterdam.

A police helicopter was also involved in the hunt for the drone around the single-runway airport that lies about 50 kilometres south of the British capital.

“The police advice is that it would be dangerous to seek to shoot the drone down because of what may happen to the stray bullets,” Mr Woodroofe said.

Police said that there was nothing to suggest that the incident was terrorism-related but Superintendent Justin Burtenshaw told the BBC he was “absolutely convinced it’s a deliberate act to disrupt Gatwick Airport”.

Around 10,000 people had by Thursday morning been affected by the shutdown that came near the height of the busy Christmas travel season.

These included 2000 travellers whose planes were not permitted to take off from Gatwick, 2000 stuck at their points of origin and 6000 diverted to other airports, airport officials said.

“My son and his partner are delayed 24 hours travelling to Gold Coast, Australia, for Christmas with her parents for the first time in three years.

“@10DowningStreet tell the police to shoot it down. UK is a laughing stock,” one man named Stuart Wilde said on Twitter.

The airport, which normally operates throughout the night, said that all flights were suspended “due to ongoing drone activity” and urged passengers not travel to the airport without first checking the status of their flights.

Gatwick, which briefly closed its runway last year when a drone was spotted in the area,

serves more than 228 destinations in 74 countries and handles 45 million passengers a year.

It is the eighth-busiest airport in Europe and sits behind Mumbai as the world’s busiest single-runway air hub.

Flying a drone near an airport, or at an altitude of over 400 feet, is illegal in Britain and carries a maximum penalty of five years in prison. Pilots have reported numerous near-misses with drones near airports in recent years in Britain, and aviation authorities warn there is a growing risk that a mid-air collision could cause a major disaster.

Strong sales of small consumer drones have led to repeated warnings about a possible threat to commercial aviation.