Apple is planning to add more security measures to help protect its users following a celebrity photo hacking incident.

CEO Tim Cook told the Wall Street Journal that Apple will use email and push notifications to let users know when someone tries to restore iCloud data on a new device, change an account password or attempts an initial log-on to an account with a new device.

Previously, there were no notifications for restoring iCloud data, but users did receive an email when someone tried to change a password or log in for the first time from a new device.

Apple expects to start sending notifications in two weeks. The iPhone maker said the new security being implemented will allow users to change passwords to reclaim control of an account or notify Apple's security team about a potential problem.

On Tuesday, Apple acknowledged computer hackers broke into the accounts of several celebrities, a security breakdown that the company blamed on the intruders' ability to figure out passwords and bypass other safeguards.

Apple said it found no evidence of a widespread problem in iCloud or its Find My iPhone service.

Instead, the affected celebrity accounts were targeted by hackers who had enough information to know the usernames, passwords and answers to personal security questions designed to thwart unauthorised entries, according to Apple.

Knowing this crucial information would enable an outsider to break into Apple accounts, including iCloud, and many other types of online accounts.

Apple's plans to add more security measures comes just days before the company is expected to unveil new products in Cupertino, California. A larger iPhone and a computerised watch are among the items being anticipated.