Apple is exploring launching iPhones with bigger screens, as well as cheaper models in a range of colours, over the next year, four people with knowledge of the matter said.
The moves by the electronics giant, which are still under discussion, take their cue from rival Samsung Electronics, underscoring how the US firm that once ruled the smartphone market is under threat from its aggressive South Korean competitor.
Samsung has overtaken Apple in market share through the popularity of its bigger-screen Galaxy "phablets" and by flooding the market with a range of products at different prices.
Apple is looking at introducing at least two bigger iPhones next year - one with a 4.7-inch screen and one with a 5.7-inch screen - said the people, including those involved in the supply chain in Asia.
They said suppliers had been approached with plans for the larger screens but noted it was still unclear whether Apple would launch its flagship product in the larger sizes.
"They constantly change product specifications almost to the final moment, so you're not really sure whether this is the final prototype," said one person.
Apple declined to comment.
Apple's possible shift to offer what is often referred to as "phablets" - chunkier smartphones not quite big enough to qualify as tablets - comes as the firm faces pressure to deliver more than one new handset model a year. Critics say its pace of innovation has slowed since the death of legendary co-founder Steve Jobs.
The iPhone 5, launched in September last year, has a 4-inch screen, one of the smaller ones among the best-selling smartphones in the market, where consumers spend more time browsing the web and streaming content. Samsung's Galaxy S4 and Note 2 have 5-inch and 5.5-inch screens, respectively.
This year, Apple is expected to launch two new models, widely referred to as the iPhone 5S, with new fingerprint technology, and a cheaper version in a plastic casing, supply chain sources said.
Apple plans to dress up the cheaper phone in a range of colours to differentiate it from the more expensive model, which has traditionally come only in black or white.
The firm has discussed a price of US$99 for the cheaper phone, the timing of which could slip to next year, one of the people said.