The iPhone 6 is widely anticipated to come in two sizes, but according to one renowned Apple analyst, the larger 5.5in screen version could be delayed until October or even into 2015.

The new iPhone 6 models are widely expected to be launched in late August/early September with the 4.7in model likely to go on sale a couple of weeks later - however problems with producing the larger 5.5in screen could see the bigger model delayed.

According to a note released by KGI analyst Ming-Chi Kuo, supply constraints on key components may result in a major delay in the release of the larger iPhone 6 model.

The research note, seen by 9to5Mac, says the issues relate to "the in-cell touch panel and colouring of the device" that could push the launch date back to a post-October date which could possibly lead to as late as next year.

Last week Kuo made a similar predicion about the iWatch, suggesting that it wouldn't go into mass production until mid-November, making a 2014 launch highly unlikely.

Sapphire display

As well as issues with in-cell technology and colouring, Kuo says the 5.5in iPhone 6 screen may not prove sturdy enough in drop tests to go to market yet. Kuo predicts when the larger iPhone 6 finally ships, fewer than 20 million units will be avaialble - which could lead to even larger queues outside Apple stores than we normally see.

A recent YouTube video (below) posted by Marques Brownlee claims to show a leaked 4.7in iPhone 6 sapphire display which is ultra-thin, durable and perfectly clear.

While Kuo says some of the same issues will affect the 4.7in model of the iPhone 6, these issues are expected to be more easily resolved for the smaller size.