Origin Energy's (ASX:ORG) shares were down nearly 1% in recent trading on Friday after the Australian Financial Review reported on Thursday that the firm warned over 700 customers that their credit and debit card details could have been compromised.

A rogue employee allegedly stole encrypted data containing customers' details, including credit card numbers used to pay bills, and attempted to email them to themself, per the report. The employee had been made redundant and sent the stolen records on their last day.

The ex-employee had signed a statutory declaration saying they had deleted the file, per the report. Origin said it could not guarantee customers' details were safe and that it had reported the matter to the Office of the Australian Information Commissioner and the Australian Signals Directorate.

Origin Energy did not immediately respond to MT Newswires' request for comment.