Citigroup bank has confirmed hackers accessed bank card customers' account information in a data breach incident.
The company said hackers accessed the details of 1% of customers at Citi Account Online in May, according to the Wall Street Journal.
The names of customers, account numbers and contact information, including e-mail addresses, were viewed. But other information - such as birth dates, social security numbers, card expiry dates and card security codes - were not compromised, Citigroup said.
Citigroup has tightened security and stepped up fraud-detection efforts in the wake of the attack. Citigroup has not disclosed whether customers had reported issues with their accounts, according to other US reports.