South Korea's Samsung Electronics Co. Ltd. unveiled its latest Galaxy S smartphones, featuring a slim body made from aircraft-grade metal, in a bid to reclaim the throne of undisputed global smartphone leader from Apple Inc.

Designed from scratch in an operation dubbed Project Zero, the Galaxy S6 and its curved-edges variant are critical for Samsung's plans to reverse plunging smartphone revenues that led to its first annual earnings fall in three years in 2014.

A warm initial reception sent Samsung shares on Monday to their highest in nearly nine months. Some technology publications described the phones as Samsung's best-looking to date after its previous flagship device, the Galaxy S5, failed to impress.