Samsung Galaxy S4 eye-tracking smartphone unveiled

Samsung has launched a smartphone which allows users to control its 5in (12.5cm) screen using only their eyes.

The Galaxy S4 follows on from last year's S3, a product that sold over 40 million units worldwide.

At a lavish, Broadway-themed event in New York, the company also demonstrated the phone's ability to take two different pictures at once.

Analysts widely regard Samsung to be the biggest challenger to Apple's dominance of mobile products.

The Galaxy S4 will be rolled out globally at the end of April.

Following the launch, shares in Samsung fell 1.7% in early trade in Seoul on Friday amid worries the market for phone upgrades was "flattening out".

Using "Smart pause", the user can pause a video by looking away from the screen.

Additionally, the "Smart Scroll" software analyses both the user's eyes and wrist to scroll through emails and other content, BBC reports.