HARRISBURG - Hackers gained access to the personal information of about 26,000 Pennsylvanians who use debit cards to receive jobless and workers' compensation benefits, the Pennsylvania Treasury Department said Thursday.

The incident was part of a wider security breach affecting 465,000 holders of JPMorgan Chase & Co. prepaid cash cards nationwide.

The breach affects only cardholders who used the JPMorgan Chase UCard Center website between mid-July and mid-September, the Treasury Department said. Michael Fusco, a spokesman for JPMorgan, said the bank found no evidence any information was used improperly.

JPMorgan first contacted Pennsylvania Treasury officials Tuesday, agency spokesman Gary Tuma said.

JPMorgan has referred the matter to law enforcement and would not explain details of how the breach occurred, the Treasury Department said.

The department said the personal information that might have been viewed includes card numbers, dates of birth, user IDs, and e-mail addresses. Information on external bank accounts might also have been exposed if a cardholder completed a transaction to such an account, the department said.

Cardholders are being contacted by letter with instructions and are being urged by JPMorgan Chase in the meantime to report any transactions they do not recognize by calling the phone number on the back of their card, the department said.