Whether such devices will be produced remains unclear; Apple routinely creates one-off prototypes of products it is considering.
The current iPhone 5 still has a 4 four-inch screen, while competitors like Samsung have offerings with screens of 4.3, 4.7 and even 5 inches.
"Many handset vendors are rolling out big phones to meet the growing demand," Yuanta analyst Dennis Chan told The Wall Street Journal. "To stay competitive, I believe that Apple is probably working on a larger iPhone."
Apple has also apparently ordered up a prototype iPad with a screen approaching 13 inches, considerably larger than the existing iPad's 9.7 inches.
If Apple is indeed considering larger screens, it will join a number of mobile device makers offering many size options, IDC analyst Helen Chiang said.
"In the long run, we will see touch screens in all sizes as the future vision of the technology industry is to offer the same user experience across all screens," she said. "The key is to bring down the cost and introduce compelling applications for large-screen devices."