Hiroki Totoki, who was appointed last year to turn around the mobile unit, said Sony was targeting the upper end of the market where rivals such as Samsung Electronics Co Ltd and Apple Inc dominate.

The launch of the new flagship model comes amid a painful restructuring at the Japanese consumer electronics giant which has thrown the future of its smartphone division into doubt, with top executives saying an exit cannot be ruled out.
But as the company focuses on cutting costs rather than growing its mobile market, the division still needs investment in new products and marketing to maintain Sony's brand and hold off a more rapid deterioration.

The Z4 sports a 5.2-inch full-HD display and  and is equipped with a 5-megapixel front-facing camera and a 20.7-megapixel camera on the rear.

The smartphone runs on 64-bit Qualcomm Snapdragon 810 processor backed by 3GB of RAM and Android 5.0 Lollipop. The Z4 will pack 32GB of onboard storage which can be expanded up to 128GB.

The Xperia Z4 gets its power from a 2,930mAh battery and will be available in White, Black, Copper and Aqua Green colours.

Sony said the Xperia Z4 would be available in Japan around the middle of the year, though it did not provide a launch date, details on carrier partners or price. The handset would be available in four colours and was slightly thinner than the previous Z3.