Chinese blog WeiPhone reports that the upcoming iPhone will feature a Retina display with 1.5 million pixels against 730,000 pixels for the current model.
The resolution of the screen therefore increases from 1136 x 640 pixels 1704 x 960 pixels.
The report, however, is not clear about how Apple will achieve this.
A factor of 1.5 in the number of pixels would lead to a 1704 x 960 resolution and 1.6 million pixels.
The site also claims that the screen size will remain the same, but the frame around the display will be thinner, making the phone look smaller.
According to the latest rumors, the iPhone 5S will go into mass production in June, while the global debut in stores is planned for September.