The details come from investment news service BrightWire, which cited a report out of Chinese mobile phone information site Laoyaoba.com. That source reportedly spotted two new iPhone models at Apple's suppliers.
Mockup of iPhone with 4.94-inch screen, created by Marco Arment.
The report said that Apple "may" release both models in 2013. The iPhone 5S reportedly has a design similar to the current iPhone 5, while the 5-inch iPhone is said to be lighter and thinner.
As larger iPhones like Samsung's Galaxy Note series have gained traction in the marketplace, there has been increasing speculation that Apple could go even bigger with a future iPhone model. The company increased the screen size of its flagship handset from 3.5 inches to 4 inches with the launch of the iPhone 5 last September.
Some have speculated that Apple could launch an iPhone with a bigger 5-inch display by keeping the same 640-by-1,136-pixel resolution as the current iPhone 5 screen. Stretching those pixels out to a 5-inch display would give a lower pixel density of 264-per-inch, but it would allow developers to continue to create applications for one screen resolution.
Analysts have also called on Apple to launch a big-screen iPhone, sometimes referred to as an "iPhone Plus." They believe Apple is "leaving money on the tablet" by not competing with larger devices like the Galaxy Note.