LOS ANGELES, June 19 (Xinhuanet)-- Malicious hackers may have stolen as many as 40 million credit cards' information after infiltrating the computer network of a data processing center, the MSNBC reported on Sunday.

    In the largest ever security breach of personal financial information, major credit card brands such as MasterCard, Visa, American Express, and Discovery were involved, according to the report.

    MasterCard International said on this weekend that card numbers and expiration dates were harvested by a rogue program planted inside the computer network at CardSystems Inc., a firm that process merchant requests for credit card authorization.

    The Atlanta-based CardSystems processes 15 billion US dollars in charges annually for major credit cards. When a retailer swipes a customer's card, the information goes to companies such as CardSystems for approval before getting passed along to banks.

    This attack exposed the numbers of 13.9 million MasterCards and an unknown number of other brands of cards, the MasterCard said. At least 68,000 accounts have had fraudulent charges posted to them.

    Information security experts believed all four of the major card brands were tainted in the biggest security breach by far. And the FBI is investigating.

    But hackers from around the world will trade and sell pilfered credit card numbers in online chat rooms, making it relatively easy for a single big theft to affect thousands of cards quickly. That also makes it more difficult to catch the culprits, experts said.

    Earlier this year, IT security firm Symantec and others warned that hackers are posing more serious threaten to personal financial information. Using trojans, worms, viruses, and other rogue programs, they are stealing critical information such as credit card number and online bank account password in a new-styled crime called identity theft.

    This weekend's revelation is the latest in a series of reported data breaches that began this year with word that identity thieves had accessed sensitive information on at least 145,000 people tracked by data broker ChoicePoint Inc. Major security lapses also have been disclosed at Bank of America and Citigroup, which said the financial information of 3.9 million customers was lost by United Parcel Service Inc. Enditem