Home Depot Inc said on Tuesday it was working with law enforcement to investigate "some unusual activity" related to customer data but that it could not confirm if it had become the latest retailer to be hit by a large-scale security breach. "At this point, I can confirm that we’re looking into some unusual activity and we are working with our banking partners and law enforcement to investigate," Home Depot representative Paula Drake wrote in an emailed statement to Reuters. "If we confirm that a breach has occurred, we will make sure customers are notified immediately." The statement came after security website KrebsonSecurity first reported that multiple banks had seen evidence that Home Depot may be the source of stolen credit and debit cards put up for sale on underground markets. Retail customers faced a massive data breach during last year's holiday season when hackers stole at least 40 million payment card numbers and 70 million other pieces of customer data from Target Corp .