Apple plans to use a larger screen on the next-generation iPhone and has begun to place orders for the new displays from suppliers in South Korea and Japan, people familiar with the situation said on Wednesday.

The new iPhone screens will measure 4 inches from corner to corner, one source said. That would represent a roughly 30 percent increase in viewing area, assuming Apple kept other dimensions proportional. Apple has used a 3.5-inch screen since introducing the iPhone in 2007.

Early production of the new screens has begun at three suppliers: Korea's LG Display Co, Sharp Corp  and Japan Display, a source said.

It is likely all three of the screen suppliers will get production orders from Apple, which could begin as soon as June.  That would allow the new iPhone to go into production as soon as August, if the company follows its own precedent in moving from orders for prototypes for key components to launch.

Apple's decision to equip the next iPhone with a larger screen represents part of a competitive response to Samsung Electronics. 

Samsung unveiled its top-of-the line Galaxy smartphone with a 4.8-inch touch-screen and a faster processor earlier this month.

Samsung, which this year became the world's largest cell phone maker, sold 45 million smartphones in the first quarter, and sales of the Galaxy phones outstripped the iPhone. Apple was not immediately available to comment.

Apple's move toward a larger display for the next generation iPhone was earlier reported by the Wall Street Journal. In addition to being Apple's rival, Samsung is also a major components supplier to the US computer, tablet and phone manufacturer.

The share of the production of new screens that go to each of the three manufacturers working with Apple has not been determined, one source said.

Sales of the touch-screen iPhone now account for about one-half of Apple's total sales, and the phone has been a key source of growth for the company in Asia.

A report in March by a South Korea business newspaper said Apple would use a "retina" display on the next iPhone, the same technology in its latest iPad that enhance image quality. The latest iPhone 4S was introduced in October last year. - Reuters