British Airways has confirmed it's investigating the theft of customer data from its website and mobile app.
The airline says credit card information of at least 380,000 customers has been "compromised."
The hack took place between August 21 and September 5 and targeted passengers making flight bookings via the British Airways website and mobile app.
As well as credit card information, the data stolen includes customers' names, email addresses, home addresses.
The theft didn't include passport information.
Alex Cruz, British Airways' Chairman and Chief Executive has apologised to anyone hit by the hack.
"We are deeply sorry for the disruption that this criminal activity has caused. We take the protection of our customers' data very seriously," Mr Cruz said.
Any customers who used the British Airways online booking service during that time period have been contacted by the airline.