Samsung Electronics Co Ltd unveiled its latest flagship handsets - Galaxy S9 and S9+, with an emphasis on visual applications for social media as it seeks to keep its title as the world's biggest smartphone maker.

The South Korean tech giant showcased the Galaxy S9 on the eve of the official start of the Mobile World Congress 2018 in Barcelona.

The S9 features essentially the same design as last year's previous flagship, with the full screen and curved glass edge of the S8. Samsung included a dual lens camera on the Galaxy S line for the first time.

The new handset also features a faster processor, improved cameras, an artificial intelligence-powered voice tool and software that turns selfies into animated emojis. It supports three different biometric authentication options — iris, fingerprint and facial recognition.

With real-time object detection and recognition, Samsung's AI-powered Bixby instantly generates information directly on top of the image the camera is pointing at.

"The way we use our smartphones has changed as communication and self-expression has evolved," said DJ Koh, president and head of the IT and mobile communications division of Samsung Electronics.

"With the Galaxy S9 and S9+, we have reimagined the smartphone camera. Not only do the Galaxy S9 and S9+ enable consumers to shoot great photos and videos anywhere, it's a smartphone that's designed to help them connect to others and express themselves in a way that's unique and personal."

The smartphones will be available starting March 16 in select markets and will be offered in four colors.

Although Samsung kept its supremacy over Apple Inc with about 21 percent of market share, market consultancy Counterpoint said, it faces tough competition from Chinese rivals such as Huawei Technologies Co Ltd and Xiaomi Corp in the fourth quarter.