Up to half of all flights in Europe have faced delays after a Europe-wide air traffic control system failed.

Eurocontrol, which runs the system, said that a technical problem meant that as many as half a million passengers could be affected, disrupting travellers who went away for the Easter weekend.

'Today 29,500 flights were expected in the European network. Approximately half of those could have some delay as a result of the system outage,' Eurocontrol said. The agency later said the Network Manager system was back up and running from 7pm BST.

London's Gatwick Airport said seven or eight flights an hour were being delayed as a result and told passengers to check with their airlines.

Passengers found themselves stuck on board planes waiting to take off

One passenger said she was settling down for a long delay of up to six hours

Eurocontrol - which covers 41 countries including all 28 EU nations plus others in Europe including Ukraine, Turkey and Norway, said the cause had been identified, without saying what it was.

Eurocontrol added that flight plans from before 11.26am BST were 'lost' and asked airlines to refile them.

How does Eurocontrol's Enhanced Tactical Flow Management System work? Eurocontrol's Enhanced Tactical Flow Management System compares demand for flights in a particular area with the available capacity. The system pulls together data such as flight plans, taxiing time, and flight position from numerous sources in multiple countries and collates them. It can then track planes in real time to manage the number of planes in the air to make sure it doesn't get too crowded. Precise monitoring prevents the carefully balanced system from being thrown out by planes with delayed departures or arrivals. Planes can then be herded into departure and landing slots at airports to keep the thousands of flights in Europe flowing smoothly. ETFMS also helps plan flight schedules up to a week in advance to help airlines and air traffic controllers plan each day down to the minute. Advertisement

The agency said it was a 'technical fault' and that the system had not been hacked, saying that safety was not compromised at any time.

Some 59 per cent of departing flights at Gatwick were delayed between 3pm and 4pm, according to airline data company FlightStats.

A spokesperson for Gatwick said: 'Following a failure of Eurocontrol's Enhanced Tactical Flow Management System (ETFMS), and associated flight plan system, some flights in and out of London Gatwick are experiencing delays.

'Passengers are advised to check with their airline for the latest information on flights and we apologise for any inconvenience that this may cause passengers.'

Several airports across the continent warned of problems, with Amsterdam's Schiphol saying that the 'system failure' at Eurocontrol could have 'possible consequences' for departures.

Toan Ravenscroft said: 'Currently on the runway with a full plane and a grumpy 19 month old, only to be told issues mean at least an hour sitting here.'

Rachel Waterman tweeted: 'Settling in for a 6 hour delay as European Air Traffic Control has crashed. Sorry to be that person but has anyone tried turning it off and turning it on again?.'

EasyJet passenger Caoimh Smith said: 'Sitting very frustrated at Lyon airport waiting on information for a delayed flight to Gatwick.'

Another Twitter user said they were stuck in Toulouse, France, after a Ryanair flight to London Stansted was cancelled.

Jason Byrne said he was stuck at Dublin Airport and had been given no information after a flight to Gatwick was cancelled.

And Matthew Shaw said: 'Crushing. Spent the last seven hours sat in Paris Airport as my connection flight home was cancelled. The flight is due in an hour... Just been delayed. Urgh.'

London's Heathrow Airport said there were no more delays or cancellations than usual while Birmingham Airport wrote on Twitter: 'Due to a European air traffic issue, the number of flights allowed to operate to and from Birmingham are currently restricted.

Eurocontrol said that flight plans from before 11.26am BST were 'lost' and asked airlines to refile them

'We apologise for any delays and advise to keep checking the departure boards. Many thanks.'

Dublin Airport said: 'A systems failure @eurocontrol, the organisation that manages air traffic control services across Europe, may cause some delays to the flight schedule @DublinAirport. Passengers are advised to check latest flight information with their airline.'

Luton-based carrier easyJet said in a statement: 'Due to an earlier flight failure of the Eurocontrol flight planning system, easyJet like other airlines experienced delays to some departing flights.

'Ten flights were delayed between one hour and three hours with 16 flights delayed as a knock-on effect caused by the initial delays. EasyJet will operate 1,598 flights today.

London City Airport tweeted: 'Due to a system failure at Eurocontrol, which is responsible for European air navigation, airspace capacity across Europe is reduced. We're expecting delays & cancellations to some flights.'

Some of the passengers affected by the problems tweeted about delays to their flights

'For passengers on delayed flights we are providing the latest information and refreshments as required.

'We understand that the issue has now been identified and we are working with Eurocontrol to minimise any further disruption for our passengers.

'While the situation is outside of its control, easyJet apologises for any inconvenience caused by the delays.'

The breakdown comes a day after the Easter holidays when many travellers are on the move around Europe, and as commuters across France faced disruption from a massive rail strike in protest at President Emmanuel Macron's reforms.

The disruption also comes as flights at the UK's two busiest airports could be hit with delays over the next three weeks as air traffic controllers introduce new technology.

Both Heathrow and Gatwick will suffer disruption as Nats (National Air Traffic Services) replaces paper flight information strips with a digital system at its control centre in Swanwick, Hampshire.

The Eurocontrol headquarters in Brussels are pictured. The agency said it hoped to have the system back up and running by tomorrow

Five services from London to Paris and two services from London to Brussels and Lille, have been cancelled today and tomorrow.

Trains to Disneyland Paris have also been re-routed, with holidaymakers forced to change at Paris' Gare du Nord, meaning longer journey times.

Some 29,000 people will see their trains either cancelled or re-routed today and tomorrow.

Frankfurt airport, Germany's biggest and one of the busiest in Europe, said the effects were 'limited' but added that planes from Brussels 'might not be able to arrive'.

Problems were also reported at Birmingham airport with passengers warned to check their flights

'We have delays at departures, but this is nothing dramatic. Punctuality is currently under 80 percent,' a spokesperson of Fraport, which runs the airport, told AFP.

German air traffic control operator Deutsche Flugsicherung warned of a possible 'vicious circle' of delays.

'Since 2 pm this system, the network manager, has failed in Brussels. This is the system, the department, that controls the flight schedules,' a spokeswoman said.

'You work from experience, but things are going slower. But of course, a vicious circle can arise. If nobody takes off, nobody can land. We don't know how long it'll take,' the spokeswoman added.

The airline Ryanair said: 'Some flights are currently experiencing delays and we regret we have been forced to cancel a small number of flights.'

Austrian Airlines also warned of possible delays at Vienna Airport and told passengers to check flight information online.

The main airports in Paris and Rome, and the organisation that runs all of Spain's airports, said, however, they had no initial reports of disruption.

Dublin airport was also reporting delays to flights

Among the airports affected were Amsterdam's Schipol (pictured), Brussels and Helsinki

Brussels airport said departures were limited to 10 flights an hour. The Belgian airport manages 650 flights a day, according to its website.

Several airports across the continent warned of problems, with Schiphol saying that the 'system failure' at Eurocontrol could have 'possible consequences' for departures.

Helsinki airport also said its traffic was facing delays.