London (CNN) -- News Corp. owner Rupert Murdoch apologized for the phone-hacking scandal ignited by revelations about his News of the World newspaper in an advertisement to appear Saturday in British newspapers.

"We are sorry," the advertisement reads. "The News of the World was in the business of holding others to account. It failed when it came to itself. We are sorry for the serious wrongdoing that occurred."

Murdoch, who signed the message, says that he wishes his company had acted faster and that apologizing is "not enough."

"In the coming days, as we take further concrete steps to resolve these issues and make amends for the damage they have caused, you will hear more from us."

CNN's Carol Jordan contributed to this report.