Apple Inc. is preparing to overhaul the look of its iPhone, three people with knowledge of the plans told Bloomberg.

An iPhone design change is needed to challenge competition from rivals such as Samsung Electronics Co., Bloomberg said. 

Apple has placed orders from suppliers in Asia for screens that are bigger than the 3.5-inch size now on the smartphone, said one of the people, who asked not to be identified because the plans aren’t public. Apple co-founder Steve Jobs had worked closely on the redesigned phone before his death in October, one person said.

The design change will be Apple’s first for the iPhone since 2010, when it introduced the iPhone 4. Electronics makers, led by Samsung, are moving toward bigger screens, as consumers use handheld devices for a broader array of tasks, including watching video, playing games and browsing the Web.

Apple is girding against competition from rivals such as Samsung, which have made Google Inc.’s Android the most widely used smartphone software. Samsung regained the lead in smartphones in the first quarter using screens of many sizes.

A new iPhone could be released by October, analysts have predicted.

Apple worked on the new device before the introduction in October of the current iPhone 4S model, Bloomberg said.