One airline reported a "network-wide failure" but NATS, the national air traffic controllers, said UK airspace was not closed but restrictions were in place.

UK-wide air traffic control fault may cause 'very high' level of delays - live updates

In a statement, it said: "We are continuing to work hard to resolve the technical issue. To clarify, UK airspace is not closed, we have had to apply air traffic flow restrictions which ensures we can maintain safety."

NATS earlier said: "Engineers are working to find and the fix the fault. We apologise for any inconvenience this may cause."

It did not give an estimate of how long it would take to fix the problem, or what had caused it.

European air traffic authority Eurocontrol warned of "very high" delays because of a "flight data processing system failure" in the U.K.

Meanwhile, AirNav Ireland, the country's air traffic controller, said: "NATS is currently experiencing a technical issue that is restricting the capacity of UK airspace. This is resulting in significant delays for flights across Europe that are travelling to, from or through UK airspace.

"Flights between Ireland and UK airports, and flights travelling to or from Ireland that travel through UK airspace are experiencing significant delays.

"At this time, there is no certainty as to when flights will be back on schedule so passengers who are due to travel today should contact their airlines in the first instance to check if their flights are delayed."

Loganair posted on X, formerly known as Twitter: "There has been a network-wide failure of UK air traffic control computer systems this morning.

"Although we are hopeful of being able to operate most intra-Scotland flights on the basis of local coordination and with a minimum of disruption, north-south and international flights maybe subject to delays.

"If you are flying with us today, please check our website for the latest information about your flight before setting off for the airport."

British Airways said it was "working closely with NATS to understand the impact of a technical issue that is affecting UK airspace, and will keep our customers up to date with the latest information".

Meanwhile, Dublin and Cork airports have both said they are experiencing delays to some flights.

In a post on X, Dublin Airport said: "Air traffic control issues in the UK today are resulting in delays to some flights into and out of Dublin Airport. We advise all passengers due to travel today to check the status of their flight with their airline in advance of travelling."

Cork Airport issued a similar warning.

Edinburgh Airport said it was a "developing situation affecting some flights across the UK network".

But Gatwick Airport said this afternoon that planes there are still landing and taking off.

Sky News producer Georgia Ziebart, who is stuck on a plane in Palma, Majorca that is set for London Gatwick said her flight has been told all planes that were in the air at the time the systems went down have been diverted to other countries - contradicting Gatwick's statement.

"We're on the tarmac in Palma, Majorca - we got on the plane an hour ago and shortly after we got on the plane, the pilot made an announcement to say it doesn't look like we'll be leaving for a while because there are issues with air traffic control across the whole of the UK.

"We've been sat on the plane now for about an hour, still haven't moved, still haven't had much information. But staff just said there's no point in us moving because we can't actually go anywhere.

"We're meant to fly into London Gatwick but airline staff here are saying any planes that were in the air at the time the systems went down have had to divert to France or other countries and obviously they don't want our flight to get diverted so they're keeping us here for now.

"One of the problems here is that because there were terrible storms in Majorca, loads of flights were already cancelled and delayed," she added.

"There are people who have been sleeping at the airport since yesterday so it's completely at capacity inside as well.

"Majorca is a really popular family holiday destination so there's a lot of children on board here, a lot of babies, my phone is running out of battery already and it's a three-hour flight. I haven't got any food. They've come around and offered water to everyone but that's it at the moment."

Other passengers took to social media to say they were stuck on planes on the tarmac waiting to take off on what is a busy travel day due to the bank holiday.

One passenger being held on the tarmac at Budapest said their pilot told passengers that a massive computer failure had closed all UK airspace and they faced an eight to 12 hour delay.

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