The chief executive of National Air Traffic Services (NATS) has said he cannot reveal the cause of the glitch which has affected thousands of passengers but is “not ruling out anything at this stage”.

Martin Rolfe said on Tuesday evening that an initial investigation had found that the air traffic control failure was caused by flight data received.

However, he later told Sky News: “You will understand we have very complex systems, handling something in the region of two million flights a year and the safety of those passengers is incredibly important to us.

“We are not going to rush into saying what the cause is until we absolutely fully understand.”

Night flights given go ahead to ease disruption – air traffic chaos latest

Reports have suggested the chaos may have been caused after a French airline misfiled its flight plan.

Without confirming the reports, Mr Rolfe said: “It could be a single flight plan… if it is a flight plan that has caused this, we know it is something in the flight data and we will get to the bottom of it and understand why.”

However, he added: “I’m not ruling out anything at this stage.

“We are conducting an investigation, we will conduct it incredibly thoroughly.”

Despite Mr Rolfe saying he is not ruling anything out, NATS said earlier there is “no indication” it was targeted in a cyber attack.

Hundreds of flights around the UK have been cancelled after yesterday’s air traffic control disruption. The incident on Bank Holiday Monday meant flight plans had to be uploaded to systems manually, slowing or cancelling air traffic across the country.

Thousands of passengers were affected by yesterday’s disruption – and many are still waiting for their flights today.

NATS suffered what it described as a “technical issue”, preventing it from automatically processing flight plans.

This resulted in flights to and from UK airports being restricted while the plans were checked manually.

NATS said at 3.15pm on Monday the problem was resolved, but disruption continued into Tuesday as many aircraft and crews were out of position.

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Analysis of flight data websites shows at least 281 flights – including departures and arrivals – were cancelled on Tuesday at the UK’s six busiest airports.

This consisted of 75 at Gatwick, 74 at Heathrow, 63 at Manchester, 28 at Stansted, 23 at Luton and 18 at Edinburgh.

EasyJet announced it will run five repatriation flights to Gatwick following the air traffic control fault as well as operating larger aircraft on key routes.

Aviation analytics company Cirium said 790 departures and 785 arrivals were cancelled across all UK airports on Monday.

That was equivalent to around 27% of planned flights and means around a quarter of a million people were affected.

British athletes were stranded in Budapest after the World Championships.

A group of around 40 athletes and staff from UK Athletics returned to their hotel in the Hungarian capital on Monday night because of the flight chaos.

Some of the affected athletes chose to travel directly to Zurich for Thursday’s Diamond League event.

Holidaymakers stuck in the UK and abroad described their frustration, as some had no idea when or how they would get to their destination.

Vicki Ostrowski has emailed Sky News to say she was stranded in Oslo with a “disabled, wheelchair-bound passenger with a neurological disease, an 83-year-old frail relative, plus three other family members”.

She added: “I myself will run out of essential heart medication two days before the flight they have reassigned us on 2 September at 5pm!”

Kayleigh, another reader, got in touch to say she was stuck at Las Palmas airport in Gran Canaria.

“It’s been 13 hours, it’s freezing, and we are trying to get some sleep on the cold floor,” she said.

“There are children lying on the cold floor, people making public speeches about the airline and it is sheer pandemonium.

“I have never felt so helpless. Been awake for 22 hours. We’ve now spent 14 hours in the airport. We were told if we waited 2-3 hours they would sort out a hotel.

“We have still heard nothing with ground staff saying they don’t know anything and no one has been around to check if people are okay!”