The upcoming Apple smartphones, dubbed as iPhone 6 and iPhone 5S, may be released in June or July this year.

RBC Capital Markets analyst Amit Daryanani released a research note (via MacRumors) saying he believes the low-cost iPhone 6 will see its release date in June or July 2013, but the phone will not feature Apple's signature Retina display.

"Our supply-chain checks indicate that AAPL is working to launch multiple new phones in the June/July time-frame this year," Daryanani said.

"Specifically, AAPL will launch the iPhone 5S and a more affordable but lower-income iPhone at the same time, in either late CYQ2 or Q3. The low-end iPhone will have the same 4-inch form factor as the iPhone 5 but will have plastic casing and no retina display [sic]. With a lower price-point, AAPL will be able to target a growing and important part of the Smartphone market (sub-$400 price-band)," he added.

Initial speculations claimed that the smartphones will be launched in August. Others say that the devices will arrive early next year.

Apple's upcoming smartphones are also rumoured to include a killer feature the new Samsung Galaxy S4 lacks.

In an interview with CNBC on Monday, Morgan Stanley's Katy Huberty said that she expects the next-generation iPhone to spark a big comeback for Apple.

"I do believe that AAPL is approaching a bottom," she said, referring to Apple's struggling share price. "As you have heard, they are talking about returning more cash, and we think they will do that in the coming weeks. But people don't own AAPL for that. They own AAPL for innovation."

Apple are expected to include an improved camera in the iPhone 6 and/or iPhone 5S which is rumoured to be capable of taking "Super HD" pictures. In order to take snaps at that resolution it'll need to have at least a 13 mega-pixel camera.

The lack of NFC support on the iPhone 5 was one of the biggest criticisms aimed at Apple's smartphone. Rumours suggest that the iPhone 5S could include support for the contact-less technology which can be used to pay for items in retail stores. Other features rumoured to be included in the handset is the A7 quad core chip processor, Retina or IGZO screen display among others.