The Galaxy S3 boasts a 4.8-inch screen (12.2cm)
South Korea's Samsung Electronics unveiled its latest flagship smartphone at a London launch as it seeks to cement its position as the world's best-selling mobile phone maker.
The Galaxy S3 boasts a 4.8-inch screen (12.2cm), 22 percent larger than the Galaxy S2, the hugely popular predecessor that helped the company overhaul Nokia as the world leader.
Despite the larger screen, Samsung says the phone is not much wider than its predecessor due to its smaller frame.
Other new developments include "intelligent camera features" which use face-recognition technology; and enhanced voice-activated controls.
An improved processor also allows users to watch video and write messages at the same time.
"With the Galaxy 3, Samsung has maximized the consumer benefits by integrating superior hardware with enhanced smartphone usability," said JK Shin, President and Head of IT & Mobile Communications Division at Samsung.
"What makes me most proud is that it enables one of the most seamless, natural and human-centric mobile experiences, opening up a new horizon that allows you to live a life extraordinary," he added.
The new model also uses the Android operating system, and its performance in the marketplace is perceived to be crucial to the success of the Linux-based system.
"The importance of the Galaxy S3 to Samsung cannot be underestimated," Adam Leach, principal analyst at Ovum, told the BBC.
"The company has built its reputation on producing the 'must-have' Android smartphone and in the process has become the poster child for the Android platform."
The handset's new "Smart stay" feature is designed to recognize how the phone is being used by having a camera on the front identify movement of the eyes.
It also comes with an eight mega-pixel camera with a zero-lag shutter speed to provide instant image-capturing.
Samsung Music Hub will provide a personal music streaming service and the Game Hub, Video Hub and Music Hub will soon be available globally.
Voice recognition interface "S Voice" allows the user to orally control the alarm clock, music features, text services and calendar.
The handset goes on sale in Europe in May to be followed by launches in Asia, the Middle East and Africa.
Samsung last week reported a record net profit of 5.05 trillion won ($4.44 billion) in the first quarter, thanks largely to strong smartphone sales.
Apple, which is engaged in a patents dispute with Samsung, is expected to release a new version of the iPhone later this year.