Thousands of passengers have had travel plans thrown in chaos after British Airways announced all flights from Heathrow and Gatwick will now be cancelled for the rest of the day.

British Airways previously said flights would be cancelled until at least 6pm, before announcing the grounding of planes is set to continue for hours longer.

Domestic and international flights are both affected, with British Airways saying the cancellations are due to a "major IT system failure that is causing very severe disruption to our flight operations worldwide" but there is "no evidence" that it is due to a cyber attack.

Passengers expecting to fly later tonight could also be affected as the airline's social media team is currently telling people that they are unable to confirm whether flights after 6pm will go ahead.

Frustrated passengers have complained of huge queues at check ins all day and say they've been left unable to use British Airways' website or app.

Pictures posted on social media also show holidaymakers onboard a plane waiting to be allowed to disembark a flight, while others have been left stranded on runways.
Frustrated passengers wait at Heathrow (
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PA)
There are long queues at Heathrow Airport (
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PA)
Passengers formed large queues before eventually being turned away from Heathrow Terminal 5 (
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Flynet)

Have you been affected by the flight cancellations? Contact the Mirror newsdesk on 0207 510 6223.

British Airways issued a statement just after 1.30pm today which advised passengers that terminals have become "extremely congested".

It added: "We are extremely sorry for the inconvenience this is causing our customers and we are working to resolve the situation as quickly as possible."

The issues come as thousands of families - many with young children - flock abroad for the Bank Holiday weekend and the start of half term.

Phil Davies - who was supposed to be travelling to Barbados with his wife, two children and mother-in-law from Gatwick Airport this morning - doesn't yet know when they'll be on their way.
Staff write gate information on a white board at Heathrow airport (
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PA)
Staff look concerned at Heathrow airport (
Image:
Flynet)
The long queues at Heathrow airport have been echoed around the world (
Image:
Flynet)

They went through to the gate before being informed of the IT issues by the captain and told to return to the terminal where they would receive meal and drink vouchers.

"There's nothing we can do about it," he told the Mirror Online. "Obviously it is pretty unprecedented but unfortunately this seems to be the current situation we are living in."

Last month Lufthansa and Air France suffered a global system outage which prevented them from boarding passengers.