Six US banks based in Massachusetts have sent letters to their customers warning them that their debit card information has potentially fallen into fraudsters' hands, forcing them to get new ones.

These regional banks, most of which have branches in and around the Boston area, all filed letters with the state government. 

The affected banks include Eagle Bank, The Village Bank, Savers Bank, Webster Five, Watertown Savings Bank, and Main Street Bank.

Eagle Bank, The Village Bank, Savers Bank and Main Street Bank told customers that a breach into a merchant's payment network allowed unauthorized access to their Mastercard debit card details.

Mastercard told DailyMail.com there was no breach of Mastercard's systems. It explained that there was a problem with a specific merchant the affected bank customers transacted with.