Sherif Hashim, who developed a hack for the latest iPhone OS 3.1.3, revealed in a tweet that when he tried to access the store he received a message stating his Apple ID was "banned for security reasons".
Shortly afterwards, iH8Sn0w, the developer of Sn0wbreeze - a tool to jailbrake iPhones, revealed on Twitter that he had received the same message.
Developer of tools to unlock the iPhone have been banned from Apple's app store
The move raises concerns that Apple may ban all jailbroken iPhones from accessing the App Store.
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See also: 10 'offensive' iPhone apps Apple blocked