It may also come with a 4-inch Retina display, suggests the site Apple Insider.
The new device, expected sometime in Q3, will help Apple keep up with the Samsung Galaxy S III, which comes with an even larger 4.8-inch screen that uses organic light-emitting display technology, and is thinner than the current iPhone.
The latest Reuters poll suggests that Samsung increased its lead over Apple in Q2, selling 50 million smartphones, vs. 30.5 million iPhones.
And it appears that the May launch of the Galaxy S III has Apple now in the unusual situation of playing catch-up.
Nokia (NOK) is actually #2 in the poll; Reuters sees it selling 34.3 million phones in Q2.
But it's the technology that matters. Apple and Samsung appear to be Nos. 1 and 1a in that regard.
iPhone 5 rendering photo based on leaked parts by Hesadanza.