Apple is testing a larger iPhone behind the closed doors of its Cupertino campus, as competition from competitors heats up in the smartphone space. According to The Wall Street Journal, the iPhone phablets Apple has been testing range anywhere from 4.8 inches to 6 inches, offering a much larger experience than what is currently found on the 4-inch iPhone line.

Word of a larger iPhone comes just as Apple is about to announce the iPhone 5S and budget iPhone 5C on 10 September. However, a larger version out of Apple reportedly won't come until next year. Apple has been particularly keen on the 4.8-inch screen that it has received from select suppliers for testing purposes, the report says.

Rumours saying Apple is making a phablet are nothing new, but The Wall Street Journal's sources indicate that talks at Apple aren't stopping. Interesting timing for the new report, as well: Samsung just unleashed its new Galaxy Note 3 at IFA 2013, providing a 5.7-inch, 1080p screen.

Speaking at the AllThingsD conference in May, Tim Cook, CEO of Apple, had a mouthful regarding smartphones found with a larger display.

"A large screen today comes with a lot of trade-offs," Cook said. "Customers clearly are looking at size, but they're also looking at do the photos show the proper colour, the white balance, reflectivity, battery life, brightness, the longevity of the display - so there's a whole bunch of things that are very important to the display.

"What our customers want is for us to weigh those and come out with a decision. At this point we felt that the Retina display we're shipping is overwhelmingly the best. In a hypothetical world where the trade-offs didn't exist you could see that being one of the things that differentiates."

The question is, will Apple just test the larger iPhone or is something that will actually come to market?

Cook didn't sound too opposed to a phablet in Apple's future. "We haven't so far, that doesn't shut off the future. It takes a lot of really detailed work to do a phone right when you do the hardware, the software and services around it. We've chosen to put our energy in getting those right and have made the choices in order to do that and we haven't become defocused working multiple lines."