Staples, which is based in Framingham, Massachusetts, confirmed late Monday that it is "investigating a potential issue involving credit card data and has contacted law enforcement."
“U.S. Secret Service is assisting Staples in its investigation,” an agency spokesman told ABC News.
Security blogger Brian Krebs had previously reported that there was a possible breach at Staples, following incidents at Kmart, Target and Home Depot.
"We take the protection of customer information very seriously, and are working to resolve the situation," a statement from Staples Inc. read. "If Staples discovers an issue, it is important to note that customers are not responsible for any fraudulent activity on their credit cards that is reported on a timely basis."
ABC News' Aaron Boyd contributed to this report.