Financial giant Citigroup has revealed that around 360,000 customer accounts were affected in the cyber attack it experienced last month, approximately double the previous figure cited by the bank.
Citibank said that "a total of 360,083 North America Citi-branded credit cards were affected" and indicated that it has started sending notifications to its customers, albeit after a wait of three weeks, CNN reports.
The company has started replacing the affected cards and has now issued fresh cards to 217,000 customers. Some of the remaining customers did not receive fresh cards because their cards have been replaced for other reasons or their accounts have been closed.
The company has also given a breakdown of customers by state, California coming up on top with over eighty thousand victims, which isn't a shock given California's large population.
Security breaches at large financial institutions can throw up nightmare scenarios for their customers who may find both their financial and personal security compromised. Thankfully in this case social security numbers and credit card security codes were not compromised, which has limited the damage.
Citibank has refused to disclose the cause of the security breach citing ongoing investigations.