Sept. 7 (UPI) -- British Airways promised compensation on Friday to about 380,000 customers affected by a data breach this summer.
The airline said Friday it's investigating "theft of customer data from our website and our mobile app" by a "very sophisticated malicious criminal attack" between Aug. 21 and Sept. 5.
Customers' banking information was compromised, but no travel information.
British Airways CEO Alex Cruz apologized Friday, telling a radio interviewer, "We will work with any customer affected and we will compensate any financial hardship suffered."
He said hackers stole enough information to use bank cards to make purchases.
"The airline has guaranteed that financial losses suffered by customers directly because of the theft of this data from British Airways will be reimbursed," the airline said.
The British Information Commissioner's Office is investigating the breach and could fine the airline.
Shares of British Airways fell by 4 percent in early Friday trading, wiping out about $648 million in market value. It's the latest public relations problem for the airline, and follows a power surge last year at its control center near London's Heathrow International Airport that disrupted flights and stranded tens of thousands of passengers.
British Airways is the latest British company, and the largest, to be targeted by hackers this summer. Curry's PC World and Dixons Carphone are others that announced hacks that affected millions of customers.