KEENE, N.H. – Customers of a Keene Internet service provider say thieves who hacked into their eBay accounts have widened their reach to bank and credit-card accounts.

The Monadnet customers have complained to the Internet provider and the auction Web site, only to have each company blame the other.

Investigators from eBay say they have received a “large and alarming amount of complaints” from Monadnet customers.

Monadnet officials, however, says it’s highly unlikely that security has been breached at their end.

Customer Robert Clemens of Peterborough sides with eBay. About 10 days ago, he was trying to upload a Web page on the Monadnet server when he stumbled upon a directory listing the e-mail addresses and passwords of Monadnet customers.

When he contacted Monadnet, Clemens said, “At the time, they didn’t seem to be that interested. I think it’s a case where salespeople didn’t really either recognize what I was trying to tell them or they were just apathetic.”

On Saturday, Clemens said, he received a phone call from a Monadnet official, telling him access to the addresses and passwords had been closed.

John McCatherin is a spokesman for Prexar, a Bangor, Maine, company that owns Monadnet. He said access to the addresses and passwords was limited to the 400 customers who have personal Web sites.

“While we are concerned and apologetic that this condition existed, it was a very limited potential for access,” he said. “We have no reason to expect that these files are compromised, and we’re totally confident that no access was available to billing or credit-card information. We have no reason to believe any of these customers would access these files for malicious or personal gain reasons.”

As a security precaution, Monadnet users will be required to change their passwords, he said. Monadnet, which has 7,500 customers, also switched to a more secure e-mail server last month.

Meanwhile, Monadnet customer Evelyn Pagella of Winchester has been closing accounts and filling out fraud paperwork after hackers racked up charges against her checking and credit-card accounts.

Pagella said she uses eBay regularly to sell antiques. On Jan. 2, she received an alert from PayPal that her e-mail address had changed. PayPal is a service that allows users to send and receive money through the Internet, and is popular among eBay users to conduct transactions.

The service is tied to Pagella’s checking account. Thieves had gotten into her PayPal account and transferred nearly $400. When the money in the PayPal account was gone, more was deducted automatically from her checking account.

“It’s been quite a nightmare,” said Pagella, who likely will be reimbursed for the outstanding charges.

Swanzey resident Dawn Phippard’s credit card is safe, but her eBay identity was used to sell a $2,600 computer to an Australian eBay user on Nov. 16. Someone used her account to advertise the item, and Phippard was charged $100 in fees.

Fraud experts urge customers to be vigilant in keeping track of e-mail and eBay accounts.

If identity theft is suspected, users should immediately contact eBay, said Kristin Spath, chief of the consumer protection division of the state Attorney General’s Office. The next step should be contacting organizations such as the Federal Trade Commission.

People should know that “law enforcement is out there to go after problems like this to ensure that the Internet is a safe place to do business,” she said.