Hannaford Bros. supermarket chain announced Monday a security breach that led to thefts of customer credit and debit card numbers.
Hannaford says the security breach affects all of its 165 stores in the Northeast, 106 Sweetbay stores in Florida and a smaller number of independent groceries that sell Hannaford products. The company puts the number of unique credit and debit card numbers that were potentially exposed to fraud at 4.2 million.
The company is currently aware of about 1,800 cases of reported fraud related to the security breach.
The Massachusetts Bankers Association said one-third of its 200 member banks have been contacted by Visa and MasterCard about the problem.
Ronald Hodge, Hannaford president and chief executive officer, said the company has "taken aggressive steps to augment our network security capabilities" since unusual credit card activity came to light on Feb. 27.
The Maine-based company said credit and debit card numbers were stolen during the card authorization transmission process, but no personal information was divulged.