According to the sources, the prototype iPhone screen is slightly larger than the current 4-inch model. The prototype iPad screen on the other hand is just under 13-inch – significantly larger than the current 9.7-inch screen.
The report from the Wall Street Journal follows earlier claims from Reuters that the company is developing larger screened devices.
Apple refused to comment on the claims.
Analysts have speculated that Apple is looking at larger screens as it seeks to win back market share from Samsung’s Android-based devices.
Tougher competition and continuing economic problems led to Apple announcing its first fall in profit for ten years in April.
The iPad maker is set to reveal its third quarter earnings later today. It is also likely to provide some statistics on how many iPads and iPhones have sold during April, May and June.
Analysts have speculated that Apple is looking to win back customers that may have been enticed to handsets with slightly larger screens.
The company has seen a huge amount of success with the iPad mini. Apple was forced to cut sales projections for its 9.7-inch iPad after the mini cannibalised sales.
The risk is that a larger screened device could do the same – cannibalise sales, rather than grow them.
However, BGC Financial’s Colin Gillis believes Apple will still push ahead with its rumoured plans to introduce new iPhone and iPad sizes.
“Apple has been slow to react to consumer desire for larger smartphone screens, [and] entry level price points on new phones,” Gillis wrote in an investors note. “Waiting and waiting, for the new products to launch, has become painful.”