In his first interview since a hacking attack on celebrities’ accounts led to nude pictures of movie star Jennifer Lawrence and others appearing on the internet, Cook told the Wall Street Journal that Apple will be more active in alerting users via e-mail and push notifications to suspicious behavior, such as attempts to change account passwords, log in to Apple services from unfamiliar devices, or restore iCloud data onto a new device.

He also said Apple will broaden the use of ‘two-factor authentication’ to gain access to accounts, and will “aggressively encourage’ people to use it when it brings out the new version of its iOS operating system later this month, according to the WSJ.

But Cook also argued that there was only so much a company could do, and suggested that customers need to take their share of responsibility. Although two-factor authentication is already available, most users don’t take advantage of it.

“When I step back from this terrible scenario that happened and say what more could we have done, I think about the awareness piece,” he said. “I think we have a responsibility to ratchet that up. That’s not really an engineering thing.”

The company said earlier this week that none of the cases it has investigated suggested that Apple’s own systems were breached. Rather, hackers were just successful in working out the celebs’ passwords and the answers to their security questions.

The exposure of photos plundered from users’ iCloud accounts has raised concerns about security and privacy at just the wrong time for Apple, just as it prepares to launch a new iPhone with an electronic payment facility.