Facing competition from rivals offering smartphones with bigger screens, Apple Inc. is planning larger displays on a pair of iPhones due for release this year, people familiar with the situation said.

The people said Apple plans an iPhone model with a screen larger than 4½ inches measured diagonally, and a second version with a display bigger than 5 inches. Until now, Apple's largest phone has been the 4-inch display on the iPhone 5.

Both new models are expected to feature metal casings similar to what is used on the current iPhone 5S, with Apple expected to scrap the plastic exterior used in the iPhone 5C, these people said.

The phones, expected in the second half, won't include a curved display, a feature recently introduced by rivals including Samsung Electronics Co., the people said. They cautioned that Apple's plans weren't final and that the company could change course.

The smaller of the two models is further along in development, and is being prepared for mass production, the people said. The larger-screen version is still in preliminary development, they said.