British Airways passengers have criticised the "absolute chaos" at London's Heathrow Airport after all short-haul flights this were cancelled due to a major IT outage.
The issue has also caused flight delays, with passengers stuck on planes after landing at the airport and baggage piling up.
The airline said the problem, which may also cause delays for its customers using Gatwick and London City Airport, is related to a hardware issue and is not because of a cyber attack.
Two BA flights to Dublin were among those cancelled.
Hundreds of people have been queuing outside Heathrow's Terminal 5 with staff only letting passengers into the building an hour before their flight, due to the backlog inside.
Some passengers were handed a letter from BA which said they were cancelling more flights throughout today.
It read: "Unfortunately we have also had to take the significant decision to cancel many of our other short-haul flights today while we work on the issues which is why there are no options to fly on a later service on Saturday 26th February.
"We know this is incredibly frustrating but we don't want to offer you a flight which is at risk of cancellation again and causes you further issues and uncertainty."
BA said long-haul flights are still operating, but customers may experience some delays.
In a statement, BA said: "We are extremely sorry that due to the continuing technical issues we are facing we have regrettably had to cancel all short-haul flights from Heathrow today until midday.
"Customers due to travel later today should check their flight status on ba.com before coming to the airport as we anticipate further disruption during the day."
It is BA's second outage in ten days.
