Speculation that Apple is to introduce a new, ultra-thin 15in MacBook has intensified amid reports that suppliers will begin shipping components for the devices before the end of the month.

Digitimes reports that Apple's upstream suppliers have recently started shipping a small volume of components for the device and estimates that the new model could begin shipping as early as March 2012.

However, what isn't yet clear is whether the new model will join the MacBook Air family - which already has 11in and 13in options - or be part of the MacBook Pro line, which many pundits have tipped for a complete overhaul next year.

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This isn't the first we've heard of a 15in, ultra-thin MacBook - Japanese website Macotakara reported last month that Apple had already finished development of an LCD test component.

The 15in MacBook - whichever line it joins - may have done away with the optical drive and could use solid-state storage as well.