Apple has reportedly added additional security protections to its iPhone 3GS handsets designed to prevent user modifications.
The move is said to be aimed at slowing the practice of 'jailbreaking', or unlocking the handset to allow the installation of software not officially sanctioned by Apple.
Reports from the iPhone Dev-Team research group suggest that the latest versions of the iPhone 3GS handset are shipping with an updated 'bootrom' component which prevents users removing software protections on the device.
Older 3GS handsets and previous models are still susceptible to the procedure, which can be performed by connecting the handset to a PC and running a special software tool.
The initiative is the latest in an ongoing game of cat and mouse between Apple and hobbyist developers, who began seeking ways to crack the iPhone shortly after the release of the first model in 2007.
The 'jailbreaking' procedure was initially developed to allow users to install additional software in the days before the App Store was launched.
Apple has never taken direct action to shut down the iPhone Dev-Team developers, but iPhone updates frequently erase jailbreaking software, and in some cases have damaged affected handsets.
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