UK transport networks have been thrown into chaos by the global IT outage.

There were long queues at airports, while trains were also disrupted because of the problem.

Gatwick – the second busiest airport in the UK – said it was affected.

There were long queues at Luton Airport, while Edinburgh Airport warned that queue times are longer.

Ryanair advised passengers to arrive at airports early as they switched to manual check-in.

Several US carriers grounded flights, including United, American Airlines and Delta.

Britain’s biggest train company Govia Thameslink Railway (GTR) – which owns Southern, Thameslink, Gatwick Express and Great Northern – issued an alert on the brands’ social media channels warning of disruption.

The message stated: “We are currently experiencing widespread IT issues across our entire network.

“Our IT teams are actively investigating to determine the root cause of the problem.

“We are unable to access driver diagrams at certain locations, leading to potential short-notice cancellations, particularly on the Thameslink and Great Northern networks.

“Additionally, other key systems, including our real-time customer information platforms, are also affected.”

South Western Railway said all its ticket vending machines had stopped working due to IT issues.

It advised passengers to “purchase your ticket online, on the train or speak to a member of station staff”.