US banking giant Citigroup admitted on Thursday that computer hackers had accessed information from around 210,000 US credit card customers.
"During routine monitoring, we recently discovered unauthorized access to Citi's Account Online. A limited number -- roughly one percent -- of Citi bankcard customers' account information... was viewed," the bank said in a statement.
The hackers gained access to customers' names, account numbers and contact information, including email addresses, Citi said. "The customer's social security number, date of birth, card expiration date and card security code (CVV) were not compromised."
Citi is one of the world's largest providers of credit cards, with more than 21 million accounts and is owed more than $77 billion in North America according to its 2010 annual report.
It was not immediately clear how the hackers accessed the information.
Citi also said it was contacting customers whose information was viewed and has implemented procedures to prevent a recurrence of the security breach.
"There has been no impact on any of our Asia-Pacific customers -- it's just in the US," a spokesperson added.