Apple's unannounced budget iPhone has appeared in yet another apparent leaked photograph, Digital Spy said.

The latest image, which shows the plastic-backed device in green beside an iPhone 5, was distributed online by iOS developer Sonny Dickson.

Apple is yet to officially confirm the existence of the lower-cost iPhone, but this is just one of many leaked images of the handset.

Previous reports suggest that the handset will be available in a wide range of colours, with red, blue, green, yellow and white shells previously glimpsed.

Apple is expected to unveil the budget iPhone alongside its flagship iPhone 5S later this year, with a September or October launch considered likely.

Purported leaked photographs of the iPhone 5S appeared online earlier this week.