Another online system containing customers’ digital personal information has been hacked.  This time it is Citigroup Inc. (NYSE: C) Citi Account Online – which contains Citigroup’s basic customer credit card information.

The Associated Press reports that an estimated 200,000 customers in North America were affected. Hackers viewed names, account numbers, and contact information including email addresses, but not social security numbers, birth dates and credit card security codes or expiration dates.

Anytime consumers hear that their bank records may have been accessed it is cause for concerns about identity theft.  Fortunately this time, many of Citigroup’s customers will learn from the bank that they could become a victim.

Citigroup didn’t say when the breach occurred, but that it was discovered during a routine monitoring of the system.  The bank said affected customers are being contacted and that it is putting in procedures to prevent the security breach happening again.

In contacting the customers, Citigroup obviously wants to avoid the public relations nightmare Sony Corp. (NYSE: SNE) experience earlier this year when its online PlayStation Network System was hacked.   The media company waited nearly a week after it knew about the breach before informing customers that hackers gain access to very detailed personal information.

Of course financial systems like Citigroup have more to loose from the potential identity theft caused by its own security problems. It would have to reimburse customers for any money taken from their account or charged to their credit cards.  Affected merchants, however, may not be so lucky.

Nonetheless, it’s nice to see a company trusted with customers’ personal information being more proactive about keeping customers informed.

As of this writing, Cynthia Wilson did not own a position in any of the stocks named here.