NEW YORK (CNN) -
As many as 187,000 GM MasterCard customers may have potentially had their personal information exposed, officials with card issuer HSBC Holdings said Wednesday.
About 6 million HSBC (Research) customers hold GM-branded MasterCards, according to the automaker, and letters have been sent so far to 1,200 telling them their information may have been open to compromise when they shopped with an undisclosed retailer.
There is no evidence any card accounts have actually been compromised, said a spokesman for HSBC. In the interest of "better safe than sorry," HSBC is proactively warning its customers, he said. The remaining 185,800 cardholders affected will be notified between now and mid-May, according to HSBC.
HSBC insisted the bank is not to blame for the security breach. "This is not an issue with our card," said Tom Nicholson, a spokesman for HSBC. "It's an issue with the retailer."
HSBC said it was notified by MasterCard's Fraud Management Department in March about the breach, but was not provided with details on the unnamed retailer.
GM MasterCard, in a letter to customers, said it did not know the merchant involved and urged customers to replace their credit cards as soon as possible "due to the serious nature of this situation," the Boston Globe reported.
The security breach is the latest example of private financial information being improperly accessed in recent weeks by companies that compile an sell personal information about millions of Americans.
Lexis-Nexis said Tuesday that data on 310,000 people nationwide may have been stolen -- 10 times its estimate of just a month earlier.
Household Bank, acquired by HSBC in 2002, began issuing the GM MasterCard Rewards card in 1992.
Customers earn points towards the purchase or lease of GM vehicles, and GM says more than 4 million GM cars have been bought or leased by Rewards customers since the card was launched.
For more on what you can do to protect yourself from the problems of identity theft, click here.
-- From Caleb Silver of CNN Business News