More concrete information is beginning to emerge that Apple will introduce a larger screen for its upcoming sixth-generation iPhone, moving away from the 3.5-inch screens that have been used since the device was first introduced in 2007.

The Wall Street Journal reports that sources familiar with the matter have confirmed South Korean panel maker LG Display and two Japanese firms, Sharp Corporation and the government-backed Japan Display, have already begun production of the new display which will be at least 4.0-inches in size.

They believe all three suppliers are likely to get production orders as early as June, making handset production possible by August and guaranteeing its arrival before the all-important Christmas holiday period.

The rumors appear more credible after Reuters claimed their own sources revealed the same three suppliers are already producing the screens. They believe the exact size of the new iPhone screen will be 4.0-inch from corner to corner. There's no information on the resolution of the display from either sources, however.

It's not surprising to see Apple considering a larger screen, especially since smartphones topping consumer wish lists appear to increasingly offer larger screen sizes than Apple's iPhone. The Cupertino-based firm's largest rival, Samsung Electronics, launched their latest flagship Galaxy S3 handset in the UK at the beginning of the month, sporting a 4.8-inch HD Super AMOLED display, for example.

The reports follow rumors in March that suggested the new iPhone would feature a 4.6-inch display. If anything, the move to a 4.0-inch screen seems more likely, but we'll have to wait and see how this plays out.