British Airways (BA/BAW) is investigating the theft of customer data from its website “as a matter of urgency”.
The data could include personal information and payment card details and as a result, the airline is urging customers to check with their banks.
In a statement the airline said the breach has now been resolved but that the personal details of around 380,000 customers who made bookings between the 21st August and 5th September were comprised.
The airline also made it clear that the stolen data did not include passport details.
Customers who think they may have been affected should contact their bank or credit card provider and follow their recommended advice from them.
British Airways added: “We are deeply sorry for the disruption that this criminal activity has caused. We take the protection of our customers’ data very seriously.”