British Airways has warned customers that around 380,000 card payments on its website and app were compromised during a 15-day data breach.
Here is what to do if you think you have been affected.
Which payments were affected?
BA says the breach relates to bookings made between 10.58pm on August 21 and 9.45pm on September 5.
What data was compromised?
The airline says personal and financial details of customers making bookings over the period were compromised. No passport or travel details were stolen.
I made a booking then, what should I do?
BA said it is in the process of contacting all affected customers. The airline is advising those customers to contact their bank or card provider and follow their advice.
Will I have to get a new card?
Some customers have complained of having to cancel cards as a result of the breach. The airline said affected customers should follow their bank or provider's recommended advice.
I'm a BA customer but I did not book a ticket over the affected period
The airline said the incident has been resolved and all systems are working normally. Customers due to travel can check in online as normal.
How about future bookings?
Future bookings will not be affected, BA said.