It literally shocked the United States cardholders, on Tuesday, when the Credit-card processor, Heartland Payment Systems disclosed that cyber thieves broke its system in 2008 and stole credit card information.

Heartland Payment Systems divulged that cyber thieves hacked into the computers that were used to process 100 million payment card transactions per month for 175,000 merchants.

In an interview, Heartland's president and CFO, Robert Baldwin said, "Intruders had access to Heartland's system for longer than weeks in late 2008." "The number of victims is unknown. We just don't have the information right now," He said.

According to the company, Visa and MasterCard alerted them of the fishy activities linked with processed card transactions. They started an investigation, which revealed software that compromised data that crossed Heartland's network.

Mr. Baldwin said, "We found evidence of an intrusion last week and immediately notified federal law enforcement officials as well as the card brands."

According to the company, several steps were immediately taken to secure its systems -a website - www. 2008breach. com - was created to provide information about the incident.

The company stated that "cardholders would not be held responsible for unauthorized, fraudulent charges made by third parties".

Baldwin said, "Our discussions with the Secret Service and Department of Justice give us a pretty good indication that this is part of a group that appears to have done security breaches at other financial institutions."

He said, this was a very sophisticated attack, and once the matter is sorted out, the company will notify each victim whose data were stolen to comply with data-loss disclosure laws in more than 30 states.

Heartland Payment Systems is the sixth largest credit card processor offering credit/debit/prepaid card processing, payroll, check management and payments solutions to more than 250,000 business locations in the United States.