By Poornima Gupta

SAN FRANCISCO (Reuters) - Apple Inc is gearing up to unveil a new product at a major September 12 event, a source familiar with the plan said, presaging the long-awaited launch of the redesigned iPhone.

The world's most valuable technology company typically takes the wraps off its latest smartphones around the fall, allowing the gadget to hit store shelves in time for the peak holiday shopping season.

The fifth iteration of the device that helped revolutionize the mobile industry is expected to sport a thinner, larger screen and a smaller dock connector, among other tweaks, sources and analysts have said.

The company on Monday declined to comment.

Apple's iPhone launches are among the biggest affairs on Silicon Valley's calendar, scrutinized by technology investors, enthusiasts and consumers alike.

The September 12 date may shift, the source said on condition of anonymity.

Samsung Electronics launched its latest Galaxy device in recent months, stealing a march on Apple in an intensifying battle for mobile supremacy. The pair now command more than half of global smartphone sales.

Technology blog iMore first reported the debut of the new iPhone at a September 12 event earlier on Monday.

(Reporting By Poornima Gupta; Editing by Alex Richardson)