Citigroup says 360,000 accounts were hacked in May cyber attack

NEW YORK ― Citigroup Inc. said a cyber attack in May affected almost twice as many accounts as the bank’s figures had initially suggested, as major U.S. lenders come under growing pressure from lawmakers to improve account security.

A total of 360,083 North American Citigroup credit card accounts were affected by the breach, the third-largest U.S. bank by assets said in a statement released late on Wednesday.

Of those affected, some 217,657 customers were reissued with new cards along with a notification letter, while the remaining accounts were either inactive or had already received new cards earlier, the bank added.

Citigroup had earlier said that about 1 percent of its North American accounts were affected. The bank’s annual report puts the total number of its customers at 21 million.

“It is mainly due to the actual number of accounts being more than what’s in the 2010 annual report as well as variances such as some of the accounts being closed, Citi spokesman Sean Kevelighan said in an emailed response.

Customers had their names, account numbers and contact information accessed, but Citi said that “data critical to commit fraud was not compromised” and that other consumer banking online systems were not accessed.

Citigroup also said it identified “the majority” of accounts compromised within seven days, adding that the information was accessed on the accounts by May 24 but that it only started notifying customers of the breach on June 3.

The bank is the latest in a growing list of companies to face cyber attacks in recent months, with Sony, Google Inc and Lockheed Martin all having suffered under hackers this year.