U.S. tech giant Apple is testing iPhones with screens larger than those on existing models -- as big as 6 inches -- The Wall Street Journal reported.

The Cupertino, Calif., company is considering offering iPhones with screens ranging from 4.8 inches to as large as 6 inches, the Journal reported Thursday, citing people familiar with the matter.

The move to a bigger screen would help Apple more effectively compete with South Korean rival Samsung, which has garnered the lion's share of the smartphone market by offering an array of devices at different price points and with different screen sizes.

Reports from component suppliers suggest Apple has began testing larger screens for iPhones in recent months.

The first five generations of the iPhone stayed with a 3.5-inch screen. An increase to 4 inches came with the introduction of the iPhone 5.

Apple is expected to unveil two new models of the iPhone Sept. 10 -- the iPhone 5S and possibly a lower-cost iPhone 5C -- although those products are expected to stick with the 4-inch screen.

Apple would not comment on the reports of possible larger iPhone screen, the Journal said.