Apple's long-awaited iPhone 5 could be on sale on October 21, according to leaked screenshots.

A screenshot of an email leaked to American technology blog This Is My Next by an employee of the Best Buy electronics chain reveals details of the Apple launch.

The email requests that a manager be in store at 6am on October 21 to put up an Apple image on the big screens in the electronics store.

Apple asked managers to be present at the launch of iPhone 4 at 6am last year too.

An Apple spokesperson said: "We are not commenting on rumours or speculation."

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Apple has traditionally held a press event the first or second week of September for the past five years in order to update its mobile lineup ahead of the Christmas shopping season.