Thousands of British Airways passengers had to endure cancellations, delays and long queues at airports as the airline suffered its third major computer failure in a little more than two years.

Wednesday's woes are the latest in a string of problems at BA, which was fined $230 million last month for a huge customer data breach and is bracing for potential strikes in a pay dispute with its pilots.

BA, owned by International Airlines Group, apologised to customers for Wednesday's disruption and said its technical team was working to resolve the problems as soon as possible. It urged customers to allow extra time at airports.

More than 60 flights to and from Heathrow and Gatwick were cancelled and more than 100 were delayed, according to the departure boards at the two airports. The problems started when people tried to check in for the first flights of the day and the airline was unable to say when they would be resolved.

BA would not confirm how many people have been affected but said it was experiencing a "systems issue" affecting check-in and flight departures at Heathrow, Gatwick and London City airports.

Customers have experienced issues checking in online, while others complained of being stuck on planes unable to take off for hours. Passengers from as far away as Japan and India complained of delays and problems checking in.

Stuart Jackson, a photography business manager, said he was stuck on a grounded plane at Heathrow and had missed his connecting flight, disrupting months of planning and wasting thousands of pounds.

"When I do arrive, I will have to just fly home again," he said on Twitter. "BA is a complete catastrophe and I will never fly with them again."

The IT failure occurred as tens of thousands of people in Britain prepared to jet off for summer holidays on what is one of the busiest weeks of the year for the country's airports.