CALAIS, Maine — County and federal officials are investigating an escalating number of credit and debit card fraud cases in eastern and coastal Maine.

The Secret Service is investigating cases in the Calais area, according to Tony McKim, president and CEO of The First, who said Tuesday that his bank is one of several affected by a recent surge in fraudulent charges on customer accounts in the Calais area.

Bangor Savings Bank also has experienced issues with fraud, according to Carol Colson, director of marketing and community relations.

“Fraudulent debit card transactions have escalated in recent weeks,” she said. “We are monitoring this closely.”

Neither McKim nor Colson could say how many customers have been affected.

David H. Watson, spokesman for the Secret Service’s Portland office, said Tuesday that he could not discuss details of any investigation.

“We are working something out in eastern Maine, but I can’t really comment on the specifics of the case,” Watson said. “We’re constantly working credit card fraud cases.”

The Secret Service was created to investigate and prevent counterfeiting and safeguard the financial systems of the United States, according to its website.

Both local banks reached out to their customers by issuing statements.

“Over the last two weeks, The First has been combating what appears to be a regional data breach involving a merchant and/or their card processor,” says the statement on The First website.

“The fraud cases we are seeing are centered in our Damariscotta and Calais markets. We do not have enough information to definitively name a merchant or a processor, nor would it be appropriate for us to do so,” it continues.

It is not clear from the website when The First statement was sent out, but Bangor Savings Bank issued a similar message on its Facebook page on Tuesday.

“With a recent rise in fraudulent debit card transactions, Bangor Savings Bank has been investigating a potential data breach of a regional retailer or card processor,” it said.

Both banks say they have a fraud protection system and are reviewing transactions for signs of suspicious activity.

The Sagadahoc County Sheriff’s Office was investigating a surge of credit card fraud in Bowdoinham earlier this month.

Sagadahoc County Sheriff Joel Merry said Tuesday that his office is continuing to investigate but, so far, has not discovered the source of the fraud. He said he is looking into about 80 cases.

Watson said criminals get credit and debit card information by skimming, a practice that involves installing devices on ATMs and point of sale terminals. A restaurant employee also can skim card information before he or she returns the card to the table.

Once they get the electronic data from a card, criminals can mount it on another blank card — mocking a legitimate credit card — or sell the numbers on the black market, Watson said.

McKim said it’s important that customers keep their bank apprised of their most current contact information.

“If we have your phone number, and we can see something going on with your account, we can contact you immediately,” he said.

He also advises letting the bank know immediately if a transaction is unfamiliar.

Additional information on fraud and how to protect oneself is available on the Secret Service website. Scroll down and click on “protecting yourself.”