British Airways has been forced to cancel or postpone dozens of flights following a problem with its long-haul planning system.

At least five flights from North America to London Heathrow were cancelled overnight, plus a departure from Tokyo.

Flights from Los Angeles and Mexico City to London Heathrow were among scores of delayed transatlantic services.

Five flights from the US and the Caribbean to London Gatwick were also delayed.

The knock-on effect means that eight flights from Heathrow to the US and Tokyo have been cancelled today. These including New York, Boston, Washington, Chicago Baltimore, Nashville and Denver.

Flights to cities including Boston and Vancouver have been delayed.

BA said the disruption has been caused by a ‘temporary issue’ that affected some of its long-haul flight planning systems overnight.

It added: “We’re sorry for the disruption caused to our customers’ travel plans.”

BA did not immediately respond to questions regarding the number of passengers whose travel plans have been affected.

However, it said the problem with its flight planning system had been resolved.

BA baggage issues

Meanwhile, BA said it is ‘doing everything we can’ to reunite customers with bags that were delayed at Heathrow on Sunday evening.

It blamed high winds at the airport, which it said made it harder for baggage handlers to quickly offload the luggage from aircraft.

The bag delays were described as ‘completely unacceptable’ by Which? Travel Editor Guy Hobbs.

“For some people this could ruin their Christmas, while for others who might be left without valuable items or medication, the consequences could be far more serious,” he added.

“British Airways must get its act together by responding to passengers and reuniting them with their lost luggage as quickly as possible. If items are not returned within 21 days and consequently declared lost, passengers should submit a claim for compensation to the airline within one week.”