MasterCard is investigating a possible breach of cardholder account data involving a U.S.-based payment processor, the company said Friday.
“As a result, we have alerted payment card issuers regarding certain MasterCard accounts that are potentially at risk,” the Purchase, N.Y., credit-card company said in a statement.
Law enforcement officials have been notified of the matter and an “independent data security organization” is conducting an ongoing forensic review. The U.S. Secret Service is investigating the breach, a spokesman said Friday.

The company is alerting card-issuing banks regarding “certain MasterCard accounts that are potentially at risk.”
“MasterCard’s own systems have not been compromised in any manner,” the statement continued.
A MasterCard spokesman declined to say how many cards may have been compromised or how many banks it is notifying, the Wall Street Journal reports.