ARLINGTON, Va. — Credit unions, banks and other card issuing financial institutions have begun to suffer card fraud as the result of card data compromised in the Heartland Payments Systems breach. However, insurance and other executives say the amounts are hard to quantify.

To date, Heartland Payment Systems has refused to say how many card numbers were compromised in the breach that it confirmed in January 2009 or how many card issuers might face losses. Visa and MasterCard have also not made any public statements on either topic.

But credit unions and other financial institutions around the country are beginning to suffer losses. One Web site that tracks banking security issues has collected the names of over 220 financial institutions that have been hit, and a $13 million credit union in Maine has been reported to have had more than 800 cards compromised. The CU is looking at related losses between $60,000 and $70,000.