More than 660 banks nationwide were impacted in the massive credit card data theft allegedly executed by international computer hacker Albert Gonzalez, according to a list compiled by Bankinfosecurity.com, underscoring the need for credit card and debit card users to check their statements regularly for charges that seem out of place.

The banks, which voluntarily reported their involvement to the Web site, range in size from small, single-branch, operations to nationwide behemoths. 

“This is probably just the tip of the iceberg,” said Tom Field, editorial director for Information Security Media Group. “Honestly, nobody knows how large this theft is.”

Field said the list includes only those banks that admitted to having cards potentially compromised. There could be hundreds more that have chosen not to go public, he said.  The list of banks as compiled by Bankinfosecurity.com is available on the site, but only a small portion have disclosed the number of cards affected.

Justice Department officials say Gonzalez and his crew stole more than 130 million credit and debit card numbers from card payment processor Heartland Payment Systems (HPY) -- the largest data breach in history. On Monday, Justice officials announced that Gonzalez and two others had been indicted on charges of conspiracy and conspiracy to engage in wire fraud in connection with the breach, which began in 2006.

First National Bank in Omaha, Neb., the 12th largest card issuer in the nation, reissued 400,000 credit cards after Visa (V) and MasterCard (MA) notified them that customer accounts may have been compromised.

Spokesman Kevin Langin said the company’s largest exposure was to its reputation.

“From an exposure perspective, you always have to deal with reassurance to the customer,” he said. “It’s always an image issue when a credit card is breached, but I think we were successful in reassuring our customers that there information was safe.”

The good news, Langin said, is the compromised records contained no identifying information such as Social Security numbers. For that reason, any fraud would likely have shown up on credit card statements. 

Citigroup (C), one of the largest banks to appear on the Bankinfosecurity.com list, declined to comment on any specific breach.

“For security reasons, we don't discuss details of the potential compromises, such as the number of customers potentially at risk, or our specific actions in each case to detect and prevent fraud,” said spokeswoman Janis Tarter.

Some banks reported as few as 100 cards compromised, and it's unclear if all chose to reissue affected cards.

Consumers should closely monitor credit card statements and immediately report any unauthorized information, said Paul Stephens, director of policy and advocacy for the Privacy Rights Clearinghouse. 

Debit card users should pay particular attention to account activity, as a compromised debit card could result on a cleaned out bank account.

"I wouldn't worry too much about credit cards that have been compromised," Stephens said.  "If it's a debit card, there are a whole new set of worries.  Even though you will get that money back, it may take you two weeks and in that time you may run into problems like bouncing checks and no available cash."

Stephens said asking for any credit card issued by a bank that was affected by the breach might be "overkill," but asking for a new debit card would be absolutely appropriate.

Representatives from Heartland did not return several calls for comment on the breach and Gonzalez’s indictment. The company issued a statement Monday, clarifying that the breach was not new and congratulating the justice department on the indictments.

“The commitment and persistence shown by law enforcement and other stakeholders in this matter has been exemplary,” said Chief Executive Officer Robert O. Carr. “Heartland looks forward to lending whatever support we can to this investigation as well as the broader fight against global cyber criminals.”

According to its Web site, Heartland handles some four billion credit card transactions annually. It is the fifth-largest payments processor in the United States by transaction volume, and the eighth largest by transaction dollar value.