The recent theft of credit- and debit-card numbers from hundreds of Hannaford Bros. stores has consumer advocates warning cardholders about another round of potential fraud.

A coalition of Maine banks on Tuesday advised customers to be wary of phone calls and e-mails from scam artists posing as bank officials and company representatives seeking their card data or personal information.

Sari Greene, director of the Maine Anti-Phishing Coalition, said large-scale data breaches that attract significant attention often bring out thieves who call cardholders under the guise of fraud investigations.

Greene said neither banks nor credit card companies would ask for such information over the phone or via e-mail.

She said scammers have become more sophisticated over the past few years, and are often able to reproduce the format of company e-mails or set up bogus 1-800 numbers to look legitimate.

"We don't want these potential phishing attacks to be larger than the breach itself," she said.