Two people arrested over the rogue drones over Britain’s Gatwick airport that threw Christmas travel into chaos last week have been released, leaving police baffled over who was responsible.

And despite the discovery of a disabled drone near the busy airport outside London, investigators say they are even examining the possibility there were actually no drones involved.

The alleged drones were flown on to the Gatwick airfield between Wednesday and Friday, forcing about 1000 flights to be diverted or cancelled and affecting 140,000 passengers.

Sussex Police on Sunday night released a 47-year-old man and a 54-year-old woman from the local area without charge after determining they were not involved.

“Both people have fully co-operated with our inquiries, and I am satisfied that they are no longer suspects in the drone incidents at Gatwick,” Detective Chief Superintendent Jason Tingley said.

The pair were held after information was passed to police by a member of the public, Chief Superintendent Tingley told Sky News. He said he was confident the arrests were justified.

Gatwick Airport, meanwhile, is offering a reward of £50,000 ($A90,000) for information leading to the conviction of those responsible for drones.

Chief Superintendent Tingley said told the BBC that police had not obtained footage of a drone and there was “always a possibility” the sightings of drones were mistaken. 

But he said authorities were continuing to actively follow lines of investigation and a damaged drone recovered close to the perimeter of the airport was being forensically examined.

No group has claimed responsibility for the disruption.

“We have kept an open mind throughout and that is still the case with regards to the motivation behind these incidents,” he said.

The drones were spotted at Britain’s second-largest airport on Wednesday evening, forcing it to close its runway in the run up to Christmas.

Every time the airport sought to reopen the runway on Thursday, the drones returned.

Authorities finally regained control over the airfield after the army deployed unidentified military technology to guard the area, reassuring the airport that it was safe enough to fly.

The drones caused misery for travellers, many sleeping on the airport floor as they searched for alternative routes to holidays and Christmas family gatherings.

Airlines operating at Gatwick, which is located south of London, include easyJet, British Airways and Norwegian.

The airport said it was expecting to operate a full schedule of 785 flights on Sunday, although a small number of delays and cancellations could occur as the airport fully recovered.

-with AAP