“We are now contacting all those affected to offer them a full refund or a rebooking on an alternative date, destination or airline,” British Airways said in an emailed statement on Thursday.
It did not say how many flights would be affected.
The airline, owned by International Airlines Group (IAG), was forced this week to cancel 1,700 flights to and from London’s Heathrow and Gatwick airports during two days of strike action by pilots over pay. Another day of industrial action has been scheduled for September 27.
The pilots’ union, the British Airline Pilots Association (Balpa), wants a pay deal to include profit sharing for BA pilots.
“We understand that BA has started cancelling its operations on the 27th of September today outside of the 14-day window to avoid having to compensate affected passengers,” BALPA said in a statement.
British Airways warned on Wednesday it would take some time for its flight schedule to return to normal after this week’s strikes left aircraft and crew in the wrong place.
Both Balpa and BA have said they want to resume talks over pay, but there is little or no sign of the ongoing deadlock being broken.
BA chief executive Alex Cruz has called for discussions with union bosses to continue in order to bring an end to the pilots’ strike.
He told the BBC Radio 4′s Today Programme on Monday: “The discussions must continue, they must be unconditional.
“The commitment of everyone at British Airways is to get over this particular dispute as quickly as possible.
“We urge the union to please sit down with us as quickly as we can so that we can reach an agreement”.