BEIJING/TOKYO (Reuters) – Chinese smartphone maker Xiaomi will soon release its first tablet, sources with knowledge of the matter told Reuters, expanding the fast-growing companys product lineup in a potential challenge to Samsung Electronics Co Ltd and Apple Inc. Xiaomi this week said it would hold a launch event in Beijing on May 15, but declined to give details or comment further. The four-year-old Chinese company, which reached the No. 5 spot in its home market in the final quarter of last year according to Chinese research firm Analysys, is a standout among Chinas crop of emerging smartphone makers that are expanding the market with lower-priced products. They are also creating new opportunities for parts suppliers in Japan, including display makers Sharp Corp and Japan Display Inc, as they bolster their offerings of high-specification features to compete with global brands.