Citigroup Inc. has confirmed hacking of its bank's network and said that computer hackers breached the bank's network and accessed the data of about 200,000 bank card holders in North America.

Sean Kevelighan, a U. S.-based Spokesman of Citigroup, said that the company is contacting customers whose information has been stolen. He said that the bank has implanted improved techniques to prevent the reoccurrence of any such incident.

The bank has disclosed that the names of customers, account numbers and contact information, including email addresses, were viewed in the breach. However, other information such as birth dates, social security numbers, card expiration dates and card security codes CVV. L were not accessed by the hackers.

The Financial Times has revealed that the breach was discovered by the bank in early May. Citigroup has faced criticism for not informing its customers about the breach. Before Citigroup, a number of other high profile companies like Japanese electronics and entertainment group, Sony were targeted by cyber criminals but they disclosed the matter to public. The bank may have to face problems for not informing customers on time.