Debit cards have weaker federal protections against fraud, merchant blunder and billing disputes than credit cards.

This month, several area banks canceled and reissued thousands of debit cards and personal identification numbers after being notified by Visa USA that customers accounts had been breached.

Visa has said the debit card customers have the same zero liability for fraudulent charges as credit-card customers do.

But there is no law that requires debit-card issuers to pay for any resulting damage, such as bounced check fees and merchant fees. And with the number of debit cards fast approaching 300 million, the potential for security breakdowns is increasing, consumer finance experts say.

"We're seeing a proliferation of plastic, each type with a different set of rights and protections for consumers," said Jean Ann Fox, a banking specialist for Consumer Federation of America.

Consider some differences:

* A consumer's credit-card liability is legally capped at $50, as long as the card issuer is informed within 60 days of the fraud being noticed. For debit-card users, that $50 cap is limited to two days, and then increases to $500.

* Under the federal Fair Credit Billing Act, credit-card consumers may refuse to pay bills for goods that are not received, defective or otherwise unacceptable. That doesn't apply to debit card users, who are protected separately under the less stringent Electronic Transfer Act. Although some debit-card companies, such as Visa, maintain the same standards for debit and credit customers, they are not bound to by law.

* If there is a billing error or duplicate charge, payment of the credit card bill is put on hold for as long as the case is investigated. With debit cards, the error is immediately deducted from your bank account. If checks bounce as a result, bank fees can accumulate. These are generally about $30 for each bad check. Some banks waive these fees but are not required to by law.

The potential to overdraw a checking account is the greatest risk of rising debit-card use, Fox said.

To prevent overdraft fees, Fox recommends careful bookkeeping on all debit-card purchases.

You should also avoid using debit cards for online purchases or big-ticket items, she said.