iPhone 5 rumors are building up as Apple Inc. is due to unveil the sixth generation iPhone in several weeks or a few months. After rival Samsung Electronics unveiled the Galaxy S 3 -- which has a 4.8-inch HD display, a 1.4 GHz quad-core processor, and killer features, the Cupertino, California-based company is under pressure to deliver.

Reputable news agencies have joined the iPhone 5 rumor mill, indicating that a new iPhone release date is near.

The Wall Street Journal, citing people familiar with the matter, reported that Apple has ordered screens measuring at least 4 inches diagonally from its Asian suppliers. The current iPhone models carry a 3.5-inch display.

Reuters, citing its own anonymous sources, said that the upcoming iPhone would a screen size that's 30 percent bigger.

Both Reuters and the Journal say that Korea's LG Display Co Ltd, Sharp Corp and Japan Display Inc, a Japanese government-brokered merger combining the screen production of three companies, have begun early production for the screens. The new iPhone could go in to production as soon as August, Reuters said.

While the reports appear legit, it doesn't mean that an iPhone 5 with a bigger display is cast in stone. Other than software that's being tested by developers, Apple does not provide any details about upcoming products until they are launched. Employees and supplier are also barred from leaking any details.

Rumor and news sites have also historically failed to hit the mark, and thus recent reports should still be treated as iPhone 5 rumors. Last year, some reports indicated Apple would be releasing two iPhone models (a model with significant upgrades and then a cheaper version), and others indicated an iPhone 5 with an overhauled design. Apple instead released the iPhone 4S, which is not aesthetically different from its predecessor. This year there were also reports about an iPad with a smaller screen that would compete with the cheap tablets offered by Amazon and others. But Apple only released a new iPad with the same 9.7-inch display.

Nonetheless, while it is not guaranteed, it would still be likely that Apple would be launching an iPhone with a bigger display. Rivals like Samsung Electronics, HTC and Motorola Mobility have threatened Apple's dominance in the market by releasing more powerful and larger phones.

HTC last month unveiled the HTC One X, which has Tegra 3 quad-core 1.5GHz chip and a Super IPS 4.7-inch display. The iPhone 4S just has an 800 MHz dual-core CPU. Aside from a 4.8-inch screen and a quad-core CPU, the Galaxy S 3 launched early this month has killer features that include Siri-like S voice, eye recognition, and NFC.

Motorola in a few weeks is expected to unveil a Droid RAZR HD, which would have a slim design, a massive battery, and a large 4.7-inch display.

The iPhone 5 rumors say that, aside from a bigger screen, the new device would have an all new design, 4G support (like the new iPad), a quad-core chip (or just a dual core CPU with a quad-core graphics processor like the new iPad), and NFC-support.