Several more retail chains, including Costco and Sam's Club, have temporarily taken down their online printing stores in the wake of a suspected data breach at PNI Digital Media, a third-party vendor that manages and/or hosts photo services sites.

Last week CVS Health Corp. disabled its CVSphoto.com site, and the week before Walmart Canada's walmartphotocentre.ca took a similar action after it was informed that customer credit card data had been potentially compromised. Other photo printing sites that might have been recently affected included Rite Aid Corp., Sam's Club and British supermarket chain Tesco's.

Related: CVS Online Photo Center Probes Possible Security Breach

"We take the protection of information very seriously. PNI is investigating a potential credit card data issue, and outside security experts are assisting in the investigation," said Kirk Saville, vice president, global communications at Staples Inc., which bought Vancouver, British Columbia-based PNI last year.

Some websites said they had been advised by PNI of a potential breach, while others said they acted because of recent reports. Costco and Rite Aid noted that PNI has limited access to customer information since it does not process credit cards, but the online photo service sites were temporarily taken down as a precaution. CVS and Walmart Canada asked customers to monitor their credit card transactions closely for unauthorized charges. Tesco's page simply said it was it was unavailable for routine maintenance.

The retailers' main websites and other services were not affected by the potential breach.