Don't hack iPhone, Apple warns

In a statement issued after the closing bell, the company said many of the unlocking programs circulating on the internet "cause irreparable damage to the iPhone's software".

Such damage can result in the phone becoming "permanently inoperable" when the company issues future software upgrades to the device, the statement read. Apple said it plans to release its next software upgrade later this week.

The iPhone went on the market in late June and has racked up more than 1 million in unit sales since then. The device is designed to work exclusively with AT&T's wireless network.

However, the popularity of the device has attracted technology enthusiasts who have managed to hack the phone's software in such a way to make it operate on other networks.

"Apple strongly discourages users from installing unauthorised unlocking programs on their iPhones," the company's statement read.

"Users who make unauthorised modifications to the software on their iPhone violate their iPhone software license agreement and void their warranty."

The iPhone has been a big driver of Apple's stock this year. The shares have soared more than 75% since the device was introduced at a trade event in January.

The company took a black eye earlier this month when it slashed the price on the device by more than 30%. Apple CEO Steve Jobs said the move was to accelerate market share leading into the holidays, though some interpreted the move as a sign that sales of the phone - which was priced at $600 - had slowed since the launch.

The day after the price cut, the company issued an apology to customers who had camped out just two months prior to pay full price for the device. Those customers were offered $100 worth of Apple store credit.

- Dow Jones News