Huge queues formed at airports around the world today after an IT system vital to scores of airlines crashed due to one faulty switch.

A program run by a huge tech firm called Amadeus is behind computers for British Airways, Air France, Lufthansa and other carriers, who use it every day to check passengers onto flights.

But the system was sent into meltdown today when the firm accidentally triggered a computer crash, causing long lines of upset passengers to form at airports across the globe.

Problems were reported at London's Heathrow and Gatwick airports, as well as Frankfurt, Charles de Gaulle Paris, Washington DC, Baltimore, Melbourne, Changi in Singapore, Johannesburg and Zurich.

Amadeus, the Spanish-based IT company whose systems failed, told MailOnline this evening: 'The incident was related to our internal infrastructure. It was triggered by an issue in a faulty switch during network maintenance.'

The issue was quickly resolved by technicians, but knock-on effects caused delays for many customers.

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Other airports, including Melbourne (pictured) in Australia, saw huge queues at the check in desks

This was the scene at Gatwick. The system said to have gone down is used by 125 airlines

There were also long queues at some check-in desks at Hong Kong airport today

Passengers were left standing in long queues at airports around the world as the computer problems caused gridlock.

One traveller wrote: 'If your entire system is down at REAGAN airport in DC, does that mean the planes aren't leaving on time?'

Another added: 'After 10 min of standing in queue, the Lufthansa system in the whole Frankfurt airport stops working. Fun'

One tweeted from London: 'When you've been looking forward to your holiday all year and then all computers at airport crash as you are checking in. ALL SERVERS DOWN'

British Airways, which has suffered a number of IT problems in recent years, said today's issues were caused by different problems to previous outages.

A spokesman said: 'We are working with global IT supplier, Amadeus, to resolve an issue which is affecting many airlines.

'All of our flights are operating as normal, but we are sorry for the temporary disruption to our online service.​'

In a similar incident in June this year, a computer crash at BA's Heathrow data centre was blamed on a single engineer who rebooted the system too quickly when the power failed.

This was the scene at Haneda Airport in Tokyo after the computer glitch cause delays

Long queues also formed at Melbourne airport in Australia due to the glitch

Passengers took to Twitter to tell of their frustration after queues formed at check in desks

Airlines affected by today's IT problems British Airways Air France Lufthansa KLM Vistara Qatar Southwest Quantas Advertisement

Heathrow's departures board showed nearly all planes took off between half an hour and an hour late this morning, with some flights scheduled for this afternoon delayed by a similar amount of time.

A spokesman for the airport said: 'A small number of airlines are currently experiencing intermittent issues with their check-in systems at airports around the world - including at Heathrow.

'Passengers will still be able to check-in for their flight, although the process may take slightly longer than usual.

'We are working closely with our airlines to help resolve the issue as quickly as possible. We apologise for any inconvenience this may cause.'

A Gatwick Airport spokesman told MailOnline some of their airlines reported faults, but the systems were only down for two minutes.

He added: 'This is an airline issue, not an airport issue. This isn't Gatwick software, it's hit a few airlines' check-in systems which are down. There was no major disruption at Gatwick.

'They are using Altea software and there are several airlines that use the same software for check-in and it's that which is affected. They cannot check the passengers in. Things are back up and running after a momentary IT glitch.'

One passenger posted this picture of a long queue at Zurich airport after the glitch today

A spokesman for Amadeus said: 'Amadeus can confirm that our systems are recovered and are now functioning normally.

'During the morning, we experienced a network issue that caused disruption to some of our systems. As a result of the incident, customers experienced disruption to certain services.

'Amadeus technical teams took immediate action to identify the cause of the issue and mitigate against the impact on customers.

'Amadeus regrets any inconvenience caused to customers.'

Flight delay compensation company AirHelp said passengers could be entitled to refunds.

Problems have been reported in Charles de Gaulle Paris, London Gatwick (pictured, file photo)

A spokesman for Airhelp said: 'Depending on the situation an IT glitch might not be regarded as an 'extraordinary circumstance', so if your flight is delayed or cancelled you could be entitled to up to £510 in compensation.

'In addition to this, the airline should provide you with meals, refreshments, access to phone calls and emails and if necessary, overnight accommodation.'