Apple has revealed details of an internal investigation into a stock option back-dating scandal. 

In a filing with the Securities and Exchange Commission, the company disclosed that chief executive Steve Jobs was "aware of the illegal practice". 

"I apologise to Apple's shareholders and employees for these problems, which happened on my watch. They are completely out of character for Apple," said Jobs.

Apple claims that the investigation found no wrongdoings by any current member of Apple's management, including co-founder Jobs.

The investigation centred on 15 stock option grants given out between 1997 and 2002.

Apple said that the grants appear to have been given dates earlier than when they were actually issued, resulting in a financial profit for the recipients of the options.

The investigation forced former chief financial officer Fred Anderson to resign from his current position as a board member. He served as chief financial officer from 1996 until 2004.