Credit card issuers have drawn fire for jacking up interest rates on cardholders who aren't behind on payments but whose credit scores have fallen for

Credit card issuers have drawn fire for jacking up interest rates on cardholders who aren't behind on payments but whose credit scores have fallen for other reasons. Now, some consumers complain, Bank of America is increasing rates based on no apparent deterioration in their credit scores at all.

The major credit card lender in mid-January sent letters notifying some responsible cardholders that it would more than double their rates to as high as 28%, without giving explanations for the increases, according to copies of five letters obtained by BusinessWeek.

Fine print at the end of the letter -- headed "Important Amendment to Your Credit Card Agreement" –- advised calling an 800-number for the reason, but consumers who called say they were unable to get a clear answer.

"No one could give me an explanation," says Eric Fresch, a Huron, Ohio, engineer who is on time with his Bank of America card payments and knows of no decline in the status of his overall credit.

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Bank of America spokeswoman Betty Riess confirms some bank cardholders could be receiving rate increases for reasons other than declines in credit scores, such as running higher balances with their Bank of America cards or with other creditors. She says the increases are part of a "periodic review" that assesses customers' credit risk.

Reiss declined to say if the Charlotte, N.C., bank had changed its credit standards, thereby bumping some consumers' rates, or how many cardholders were being affected by the review. Bank of America has 40 million U.S. credit card accounts.