Apple's three main drivers of growth - the Mac, iPod and iPhone - have been reduced to only one, the Mac. That's according to analyst firm BMO Capital Markets, which claims that Apple's ability to increase its revenue is significantly reduced by its inability to capitalise on some of its most popular devices.

Despite continued high sales, BMO asserts that the iPod has entered the maturing stage of its life cycle and sales will slow, while the iPhone is not yet equipped to meet the demand of consumers.

iPhone just isn't cutting it

"We continue to believe that Apple [isn't] pricing its phones aggressively [enough], and needs to sign up more carriers, both of which we believe will serve as catalysts in [the second half of the year], with a July introduction of a 3G phone," BMO told AppleInsider.

The analyst company predicted that Apple will be able to sell Macs going forward, before claiming that the computers are "the only growth driver in the near-term".

Apple did not comment on the report but, as if to make BMO Capital Markets look good, released an update to its MacBook line on Wednesday.