* SSEC -0.3%, CSI300 0.0%, HSI -0.7% * HK->Shanghai Connect daily quota used -4%, Shanghai->HK daily quota used 3.4% * FTSE China A50 +0.1% SHANGHAI, May 20 (Reuters) - Hong Kong stocks fell on Thursday, as energy and materials firms retreated after Beijing vowed to curb sky-high commodity prices by stabilizing the market. ** The Hang Seng index dropped 0.7% to 28,382.02 points, while the Hong Kong China Enterprises Index lost 0.4% to 10,613.27. ** The Hang Seng energy index and Hang Seng materials index slumped 4.5% and 4.7%, respectively, by midday. ** Yanzhou Coal Mining Co Ltd, Jiangxi Copper Co Ltd and Zijin Mining Group Co Ltd shed between 4.2% and 8.4%. ** China will strengthen its management from both supply and demand sides to curb “unreasonable” increases in commodity prices, and prevent the pass-through to the consumer, the cabinet said on Wednesday. ** The comments drove prices of commodities including steel and iron ore to extend recent losses after surging this year on the back of post-lockdown recoveries in demand and easing liquidity globally. ** Digital currency and blockchain-related stocks also pulled back after a cryptocurrency slump. ** However, analysts saw a very limited impact on the broader market from the cryptocurrency fallout. ** Chinese investors’ participation in cryptocurrencies is very limited due to Beijing’s continued clampdown, said Yan Kaiwen, an analyst with China Fortune Securities. ** Yan said Bitcoin mining has consumed too much of China’s resources, including coal, at a time when Beijing seeks carbon neutrality. ** Despite the weakness, mainland investors continued their buying, purchasing a net 4.5 billion yuan ($698.94 million) worth of Hong Kong shares on Thursday, according to Refinitiv data. ** Shares of China’s e-commerce co JD.com Inc rose as much as 4.1% to HK$281.80, their highest since May 12 as first-quarter revenue topped estimates. ** On the mainland, the CSI300 index was unchanged at 5,174.50 points at the end of the morning session, while the Shanghai Composite Index lost 0.3% to 3,500.86 points. ** The CSI300 energy and the CSI A-share resource industries index dropped 2.6% and 3.1%, respectively. ($1 = 6.4383 Chinese yuan renminbi) (Reporting by Luoyan Liu and Andrew Galbraith; Editing by Devika Syamnath) Our Standards: The Thomson Reuters Trust Principles.