Visa USA has said that its customers may also be affected, and said that it would be working with law enforcement and banks to prevent any fraud from the data breach. Bills are currently before Congress to strengthen data security and require notification to consumers whenever a security breach occurs.
The scope of a computer system breach at a national retailer widened yesterday to involve the customers of a second major credit card firm, but those companies refused to divulge the name of the retailer.
The existence of the security breach first surfaced this week when HSBC North America began notifying 180,000 of its GM MasterCard customers that their credit card information had potentially been compromised.
MasterCard officials said yesterday they uncovered the breach and informed member banks of its existence, but they said it was up to each bank to determine how it wanted to respond.
A second company, Visa USA, late yesterday said it had been notified by the same merchant that a data security breach had occurred, potentially exposing the credit card data of Visa customers to thieves.
Visa said it would begin working with the merchant, law enforcement officials, and member banks to monitor and prevent card-related fraud.
''Because of the nature of the ongoing investigation, MasterCard cannot disclose specific details," the company said in a statement.
News of the breach at the unidentified national retailer surfaced as the Senate Judiciary Committee held a hearing in Washington where lawmakers vowed greater regulation of personal data brokers and also pledged to pass legislation requiring companies to notify consumers when their personal data are compromised.
Two bills are pending, both of which would require consumers to be notified when a breach of personal information occurs.
Tom Nicholson, a spokesman for HSBC, said yesterday that the bank was urging less than 1 percent of its customers to replace their credit cards.
Nicholson said letters were immediately sent to 12,000 GM MasterCard cardholders and would be sent to a total of 180,000 by mid-May.