Apple has warned iPhone owners who have used unauthorised programs to unlock the cellular service feature of their handsets that they may end up with a phone that doesn't work after the company's next software update for it.

Since the iPhone debuted in June, hackers have posted a number of methods online to make it possible to use the iPhone on cellular networks other than AT&T, which is the exclusive official carrier for the iPhone.

The news will come as a blow to scores of Australian iPhone enthusiasts who have brought the $US399 phones out to Australia and hacked them so that they can work on local mobile networks.

Apple executives say they have discovered that many of those unauthorised unlocking programs cause some software damage to iPhones.

Now, a software update that Apple plans to issue later this week that will add features such as accessibility to the iTunes Wi-Fi Music Store may end up making the touch-screen mobile phone completely inoperable if it has been hacked into.

"This has nothing to do with proactively disabling a phone that is unlocked or hacked," Phil Schiller, Apple's senior vice president of worldwide product marketing, said in an interview.

"It's unfortunate that some of these programs have caused damage to the iPhone software, but Apple cannot be responsible for ... those consequences."

Launching the iPhone in London last week, Apppel CEO Steve Jobs indicated that Apple was looking at ways to beat the hackers.

"This is constant cat-and-mouse game. We play it on iPods with our digital rights management and when somebody hacks it we have to go ... and stay a step ahead," he said.

"It's the same way here, people are going to try and break in and it's our job to try and stop them."

As with any Apple product, hacking into the iPhone will void its warranty, Apple said.

Apple has sold over a million iPhones since it hit the market June 29.

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