Apple is on track to release an "iPhone 5" in September, according to reports from component suppliers in Asia who are gearing up to build the next generation of the company's smartphone.

Although reports vary on the naming – with some sources suggesting that it will be called the iPhone 4G or 4S – the Guardian has been told that the form of the device is very similar to the existing iPhone 4, which was released in summer 2010.

The suppliers are also understood to be preparing for another iPhone release during 2012, though the timing on that is less certain. Some are suggesting that the next model could come out in March.

The Guardian understands that while the new version will look very like the iPhone 4, it may dispense with some of the visible buttons on the side of the device for volume control.

Other reports on Bloomberg suggest that the new phone will use an A5 processor like that included in the iPad 2 released in March and feature an 8MP camera (compared with 5MP in the iPhone 4). Some reports suggest that it is testing a higher-resolution or larger version of the screen than that in the present model.

The new devices will include Apple's new iOS 5 software, which includes its iCloud capability to synchronise data between devices, and to activate and update phones without requiring connection to a computer, as well as offering photo sharing and Twitter messaging across many apps.

Richard Windsor, global technology marketing analyst at Nomura Securities, said he expected the version sold in September to have the same price as the existing one, which Apple sells for about $600. "We think there will be an iPhone 5 in September – the suppliers have been ramping up for it," he said.

The key question, said Windsor, will be whether Apple introduces a mid-range phone at about $300 in order to capture a larger share of the market. If that happens, he suggests, Apple's share of the smartphone market – currently about 19% of the 100m devices sold per quarter – could explode as the market itself grows in this year and 2012.

But Windsor said he has not seen any sign that Apple is preparing a "mid-range" phone so far for launch early next year, which would be needed to capture a significant slice of the market.

Phones running Google's Android operating system have taken a dominant share of the smartphone market in the past six months, with a 31% share in the first quarter. Android pushed ahead of Nokia, whose Symbian operating system had been the leading smartphone platform for years, in the first quarter of this year. Apple is in third place, though analysts expect Apple to pass Nokia in the current quarter which ends in just over a week.

The smartphone market is expected to grow 55% this year to 472m and to hit 1bn units by 2015, according to the research company IDC. With Android devices and, from October, Nokia devices running Microsoft's Windows Phone software competing for that market, it may become imperative for Apple to produce a mid-range device to capture more revenue, as it did in the music player market when it launched the iPod Mini, iPod Nano and iPod Shuffle.

IDC expects that Android will grow to more than 40% of the market by the end of 2011, while Windsor at Nomura expects Apple to pass Nokia to take second place in smartphone sales to Samsung.

The new iPhone would be hotly anticipated but Apple will want to play down the reports ahead of the summer season in case it affects sales.