SEEKONK - Shoppers say they worry that conveniences like debit and credit cards make them vulnerable to theft, but they have become so accustomed to not using cash that they will likely continue using the cards.

The shoppers spoke outside Stop & Shop Supermaket in Seekonk, where company officials say there is evidence of tampering with its debit card machine.

Two Stop & Shop stores in Rhode Island also report financial account and personal identification numbers have been stolen from credit and debit cards.

"This makes me think twice," Pam Collins of Greenville, R.I., said of the news. "I've been using the card more often because it is so convenient. I'm going to be more careful in the future."

Collins said she still uses her debit and credit cards, but checks her accounts more frequently to make sure nothing is wrong. Karen Laroche of Warren, R.I., said even using store courtesy cards - which provide discounts - makes her nervous.

"They can track all kinds of information with those cards," she said.

On the other hand, Laroche said she enjoys the discounts the store cards provide.

Debit cards are also a great convenience, she said, because she rarely carries a lot of cash with her.

Laroche said she would like to limit her use of debit cards, "but I haven't found what the alternative is yet."

One Stop & Shop customer who did not want to give her name said she ran into trouble recently when someone stole personal and financial information about TJ Maxx customers.

She said she was able to cancel her account before anyone could steal money from her, but the experience left her concerned about the cards.

Security experts say the incident involving TJ Maxx stores in January was far more serious because it involved a breach of a computer database containing millions of credit and debit cards.

Stop & Shop released a letter to its customers saying fraudulent activity has been discovered at electronic funds transfer machines at stores in Conventry and Cranston, R.I.

It also said tampering has been discovered at their Bristol, Providence, Warwick and Seekonk stores, although no fraudulent transactions were found at those stores. The company said it is auditing its machines and has notified local police and the U.S. Secret Service.

"We apologize to our customers who may be affected by this criminal activity that has occurred in these stores," the letter states.

"We recommend that customers who used electronic payment cards in our Rhode Island stores and our Seekonk, Massachusetts, store carefully monitor their bank or credit card statements relating to such cards and that they contact the applicable bank or credit card issuer immediately in the event of any fraudulent transactions."