As many as 1 million student loan borrowers from Sallie Mae may have found that their credit scores plunged after the loan company erroneously reported they were delinquent in their payments.

Tom Joyce, senior vice president of corporate communications for Sallie Mae, said yesterday that the lender discovered Friday that a recent download of account information to one of the credit bureaus, Equifax, included a computer code that caused some accounts to be considered delinquent when they were not.

Those affected have graduated loan repayment schedules. In an online forum about FICO, the scoring agency, some reported sudden drops of more than 100 points in their credit score.

"We immediately contacted the credit bureau to correct the information," Mr. Joyce said, noting the three other credit bureaus were alerted as well.

He said the number of customers affected was still being determined but was believed to be no more than 10 percent of Sallie Mae's 10 million borrowers.

"We certainly and fully understand the importance of one's credit rating. We're working with urgency to resolve this situation," Mr. Joyce said.

Mr. Joyce yesterday said he expected that the correct file would reach Equifax in the next day or two and that credit ratings would be restored without any historical record or negative remarks.

Those who think they may be affected may contact Sallie Mae's customer service line at 1-888-2-sallie.

Mr. Joyce said contacting Sallie Mae was preferable to contacting a credit bureau because pulling a credit report can slightly lower a credit score or, in some cases, might cost consumers money.

For those in the process of trying to get loans, he said Sallie Mae would "gladly and promptly" supply credit references if the agency made errors in their cases.